Pneumatic radial tire

ABSTRACT

Inside a tread portion and outside a belt layer along the radius direction thereof is formed a belt layer comprising a band ply formed by winding spirally a tape- and belt-form ply wherein one ore plural band cords are stretched and arranged to be embedded in a topping rubber. In this band ply, the elongation resistance value K (unit: N′ cord number/cm) specified by the following equation is set within the range of 99 to 700 when the sectional area of the band cord or each of the band cords is represented by S (unit: mm 2 ), the modulus thereof when the elongation thereof is 2% is represented by M (unit: N/mm 2 ), the band cord arrangement density per cm of the band ply is represented by D (unit: cord number/cm).
 
 K=S×M×D/100   (1)

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/JP02/05759 which has an Internationalfiling date of Jun. 10, 2002, which designated the United States ofAmerica.

TECHNICAL FIELD

The present invention relates to a pneumatic radial tire making itpossible to decrease road noise while reducing deterioration in transitnoise and rolling resistance.

BACKGROUND ART

As illustrated in FIG. 41, it has been hitherto suggested for apneumatic tire to dispose a band layer g wherein low-elastic band cordsmade of, e.g., nylon are arranged in the circumferential direction ofthe tire outside a belt layer b. In recent years, as this band layer g,a band ply f has been used, the ply f being formed by winding asmall-width and belt-form ply c, wherein the band cords are stretchedand arranged in parallel and coated with a rubber, spirally on theoutside of the belt layer. In this band layer g, the band cords arrangedsubstantially along the equator of the tire fastens and restricts thebelt layer b. It is known that this causes the suppression of a rise ofends of the belt layer b (the so-called lifting) at the time ofhigh-speed traveling and an improvement in high-speed durability.

When such a band layer is deposited, the power of restraining the beltlayer is raised up so that the rigidity of the tread face is made high.Thus, it has been made evident that, for example, road noise (noise in acar) of about 250 Hz in frequency is decreased and, depending on thearrangement of the band, transit noise (noise outside the car) is alsodecreased. It has been made clear that, in particular, the noisedecreasing effects can be made larger by adjusting the modulus.

In other words, the band ply intends to improve the high-speeddurability of the tire as described above, but it has been made evidentthat road noise (noise in a car), transit noise (noise outside the car),which is heard outside the car, the rolling resistance thereof, and soon change to some degree depending on the specification of the band ply,for example, the adaptation of high-modulus cords made of, for example,polyethylene naphthalate.

As this band ply, a full band ply, which covers almost all width of abelt layer, and an edge band ply, which covers only both ends of a beltlayer, are known. There are pneumatic radial tires using only a fullband ply, pneumatic radial tires using an edge band ply, and pneumaticradial tires using a full band ply and an edge band ply. Practical useand development of such a band ply are essential, in particular, forhigh performance tires.

DISCLOSURE OF THE INVENTION

(Basic Invention)

Thus, road noise, transit noise and rolling resistance were researchedand developed. As a result, it has been found out that when elongationresistance value K of a band ply which is defined by the followingequation (1) is used as a parameter, the elongation resistance value Khas a correlation with road noise, transit noise and rolling resistance:K=S×M×D/100  (1)

wherein S represents the sectional area (mm²) of each of the band cords,M represents the modulus (N/mm²) when the elongation of each of the bandcords is 2%, and D represents the band cord arrangement density per cmof the ply width (cord number/cm).

The band layer is formed by winding a tape- and belt-form ply, whereinone or more band cords are stretched and arranged and then embedded in atopping rubber, spirally. This basic invention can be applied torespective high performance pneumatic radial tires using only a fullband ply, only an edge band ply, and a full band ply and an edge bandply. It has been found out that the elongation resistance value K (unit:N′ cord number/cm) of the respective band plies is set within the rangeof 99 to 700 and this range is a range making it possible to produce aband layer which can be used in a high performance pneumatic radialtire, and such a range gives in substantially preferable results, fortires, about road noise, transit noise and rolling resistance.

(First Invention)

In the case that the band ply is a full band ply, which is used in manycases since the ply has superior dimensional stability when it issubjected to vulcanization forming, the basic invention in this case isnamed a first invention.

In the case that this full band ply is used, it has been found out that,as shown in FIG. 4, the degree of deterioration in transit noise androlling resistance tend to increase, while the degree of decrease inroad noise tend to decease as the elongation resistance value Kincreases. By forming a band ply with an elongation resistance value Kwithin a range such that the deterioration degree of transit noise androlling resistance is gentle and the decrease degree of road noise issharp, the elongation resistance value K calculated by the equation (1)is set within the range of 99 to 334 in the case of the full band ply ofthe first invention in order to exhibit the road noise decreasing effecteffectively while keeping the increase in transit noise and rollingresistance below a minimum tolerance limit, thereby giving an optimalperformance balance.

This results in a relief of an inconvenience that in the case where aband layer of a full band ply is used in conventional pneumatic radialtires to decrease road noise, transit noise and rolling resistanceincrease.

That is, an object of the first invention is to provide a pneumaticradial tire capable of bringing out the effect of decreasing road noiseeffectively while deterioration in transit noise and rolling resistanceis kept below a minimum tolerance limit, wherein the elongationresistance value K of a full band ply is set within a given range as abasic manner.

Furthermore, in the first invention, the number of band cords of thebelt ply is J (two or more), and further the full band ply ischaracterized in that in a band central area having a widthcorresponding to 20 to 80% of the belt layer width BW, the center ofwhich area is the equator of the tire, the band cord(s), the number ofwhich is at least one, that is, j, is/are cut from the belt ply.

By setting as described above in a full band ply, it is possible in atire having the full band ply to decrease road noise (noise in a car)and prevent increase in transit noise (noise outside the car) and therolling resistance of the tire.

(Second Invention)

In the case that the above-mentioned band ply is an edge band ply, whichintends to prevent the lifting of a belt layer at both ends thereof, thebasic invention in this case is named a second invention.

It has been found out that the use of this edge band ply is effectivefor decreasing not road noise (noise in a car) but transit noise (noiseoutside the car), which is different from the case of the full band ply.This edge band ply consists of a pair of right and left band plies whichcover both ends of a belt layer, and further, by regulating theelongation resistance value K calculated from the equation (1) within agiven range, transit noise (noise outside the car) and road noise (noisein a car) can be effectively decreased.

Provided is a pneumatic radial tire wherein the elongation resistancevalue K, and the width ratio of the edge band ply width Wb to the beltlayer width WB (Wb/WB) are set as follows:

a) the edge band ply is made in such a manner that the elongationresistance value K is set within the range of 120 or more and less than246 and the width ratio Wb/WB is set wherein the range of 0.2 or moreand 0.5 or less, or b) the elongation resistance value K is set withinthe range of 246 or more and less than 276 and the width ratio Wb/WB isset within the range of more than 0 and 0.5 or less, or

c) the elongation resistance value K is set within the range of 276 ormore and 450 or less and further the width ratio Wb/WB is set within therange of more than 0 and 0.41 or less.

The edge band ply is made as follows:

d) the elongation resistance value K is set within the range of 120 ormore and less than 246 and further the width ratio Wb/WB is set withinthe range of 0.41 or more and 0.5 or less, or

e) the elongation resistance value K is set within the range of 246 ormore and 450 or less and further the width ratio Wb/WB is set within therange of more than 0 and 0.14 or less.

In this way, the edge band ply is used in the second invention todecrease transit noise and road noise.

(Third Invention)

In the case that the band ply uses both of a full band ply and an edgeband ply, which is separated at the center and covers both ends of abelt layer, the basic invention in this case is referred to as a thirdinvention. It has been found that by setting the elongation resistancevalue K from the (1) equation to 110–386, the full band ply causes adecrease in road noise and further the edge band ply prevent increase intransit noise (noise outside a car), which is heard outside the car, androlling resistance.

In order to produce the above-mentioned effects and advantages in thepneumatic tire of the third invention, about the elongation resistancevalue K (unit: N′ cord number/cm²) of the edge band ply and the widthratio of the edge band ply width Wb to the belt layer width WB (Wb/WB),

in the case that the elongation resistance value K is 110 or more and170 or less, the width ratio (Wb/WB) can be set to more than 0 and lessthan 0.5,

in the case that the elongation resistance value K is more than 170 and280 or less, the width ratio (Wb/WB) can be set to more than 0 and 0.07or less, or set to 0.47 or more and less than 0.5, and

in the case that the elongation resistance value K is more than 280 and386 or less, the width ratio (Wb/WB) can be set to 0.47 or more and lessthan 0.5.

In another embodiment, in the case that the elongation resistance valueK is 110 or more and 280 or less, the width ratio (wb/WB) can be set tomore than 0 and less than 0.5 or less,

in the case that the elongation resistance value K is more than 280 andless than 340, the width ratio (Wb/WB) can be set to more than 0 and 0.4or less, and

in the case that the elongation resistance value K is more than 340 and386 or less, the width ratio (Wb/WB) can be set to more than 0 and lessthan 0.28.

In a further embodiment, in the case that the elongation resistancevalue K is 110 or more and 170 or less, the width ratio (Wb/WB) can beset to more than 0 and 0.5 or less, and

in the case that the elongation resistance value K is more than 170 and280 or less, the width ratio (Wb/WB) can be set to more than 0 and 0.07or less, or 0.47 or more and less than 0.50.

The above-mentioned structure makes it possible to exhibit the effect ofdecreasing road noise effectively while keeping transit noise androlling resistance below a minimum tolerance limit in a pneumatic radialtire having a full band ply and an edge band ply.

From further repeated researches on band plies, it has been found outthat when a band layer has a full band ply, the winding pitches ofbelt-form plies are made different between the center of the treadportion thereof and both outside portions thereof, thereby decreasingroad noise while suppressing increase in transit noise at a lowest levelmore effectively.

That is, a band ply comprises high density portions wherein the windingpitch of its belt-form plies is 1.0 time or less the width of thebelt-form plies and a low density portion formed between the highdensity portions wherein the winding pitch of the belt-form plies isfrom 1.2 to 2.6 times the width of the belt-form ply, and at this timethe elongation resistance value K (unit: N′ cord number/cm) is set tofrom 130 to 700. This can be applied to each of the first and thirdinventions as long as the elongation resistance values K thereofoverlap. (This invention is referred to as the “invention about densitychange”.)

From results of further development on band plies, it has been found outthat as illustrated in FIG. 42, in a band ply wherein high-modulus bandcords are adopted, a rubber exfoliation j is readily generated between awinding terminal portion c1 which constitutes a one-circumferenceportion ahead of the winding terminal of a belt-form ply c and abelt-form ply c2 wound inside it. (Such a damage may be referred to as a“belt edge looseness” hereinafter.) It has been made evident that thisrubber exfoliation j is formed as follows: an exfoliation starts from amicroscopic rubber exfoliated portion al generated near outer end be ofa belt layer b, which has a poor adhesion to the rubber, and then theexfoliation grows between the winding terminal portion cl of thebelt-form ply c, at which restraining power is readily lowered since theend is free, and a belt-form ply c2 so as to reach an outer faceposition a2 of the band ply f.

For this reason, in a tire having a belt ply in which the elongationresistance value K (unit: N′ cord number/cm) thereof is from 166 to 467(this can be applied to the respective inventions as long as theelongation resistance values K of the first to the third inventionsoverlap), the tire being a pneumatic tire wherein the above-mentionedband ply is positioned in such a manner that a winding terminal portionwhich constitutes a one-circumference portion ahead of the windingterminal of the above-mentioned belt-form ply does not directly contactthe outer end, along the tire axial direction, of the above-mentionedbelt layer, at least one portion of a winding starting end portion whichconstitutes a one-circumference portion in the rear of the windingstarting end of the belt-form ply is covered with a belt-form ply woundafterwards, and the winding terminal portion is disposed outside theouter end of the belt layer in the tire axial direction. (This inventionis referred to as the “invention about overlap of a band with a beltlayer”.)

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating an example of the pneumaticradial tire of the present invention.

FIG. 2(A) is a perspective view illustrating a belt-form ply used in aband layer.

FIG. 2(B) is a sectional view thereof.

FIGS. 3(A) to (C) are sectional views illustrating a manner of winding abelt-form ply.

FIG. 4 is a graph showing a relationship between road noise, transitnoise and rolling resistance using elongation resistance value K as aparameter.

FIG. 5 is a sectional view illustrating an example of the pneumaticradial tire of the present invention.

FIG. 6 is a graph showing a relationship between elongation resistancevalue K, width ratio Wb/WB, and road noise.

FIG. 7 is a graph showing a relationship between elongation resistancevalue K, width ratio Wb/WB, and transit noise.

FIG. 8 is a graph showing a relationship between elongation resistancevalue K, width ratio Wb/WB and rolling resistance.

FIG. 9 is a sectional view illustrating an example of the pneumaticradial tire of the present invention.

FIG. 10 are schematic sectional view illustrating a manner of winding abelt-form ply.

FIG. 11 is a graph showing a relationship between elongation resistancevalue K, width ratio (Wb/WB), and road noise.

FIG. 12 is a graph showing a relationship between elongation resistancevalue K, width ratio (Wb/WB) and rolling resistance.

FIG. 13 is a graph showing a relationship between elongation resistancevalue K, width ratio (Wb/WB) and transit noise.

FIG. 14 is a sectional view illustrating an embodiment of the pneumaticradial tire.

FIG. 15 is a schematic sectional view for explaining a winding form of abelt-form ply.

FIG. 16 is a developed view of the inner structure of the tire.

FIG. 17 is a schematic sectional view for explaining another windingform of the belt-form ply.

FIGS. 18(A) and (B) are schematic sectional views for explaining afurther winding form of the belt-form ply.

FIG. 19 is a sectional view illustrating a band ply of ComparativeExample.

FIG. 20 is a sectional view illustrating a band ply of ComparativeExample.

FIG. 21 is a sectional view illustrating an embodiment of the pneumatictire.

FIGS. 22)(A) to (C) are schematic sectional views illustrating windingmanners of a belt-form ply.

FIG. 23 is a schematic view illustrating an example of the band ply.

FIG. 24 is a schematic view illustrating an example of the band ply.

FIGS. 25(A) and (B) are partial sectional views illustrating an enlargedend portion of a belt layer.

FIG. 26 is a partial sectional view illustrating an enlarged end portionof a belt layer.

FIG. 27 is a schematic view illustrating an example of the band ply.

FIG. 28 is a schematic view illustrating an example of the band ply.

FIG. 29 is a schematic view illustrating an example of the band ply.

FIG. 30 is a schematic view illustrating an example of the band ply.

FIG. 31 is a schematic view illustrating an example of the band ply.

FIG. 32 is a schematic view illustrating an example of the band ply.

FIG. 33 is a schematic view illustrating an example of the band ply.

FIG. 34 is a schematic view illustrating an example of the band ply.

FIG. 35 is a schematic view illustrating an example of the band ply.

FIG. 36 is a schematic view illustrating an example of the band ply.

FIG. 37 is a schematic view illustrating an example of the band ply.

FIG. 38 is a schematic view illustrating an example of the band ply.

FIG. 39 is a schematic view illustrating an example of the band ply.

FIGS. 40(A) to (C) are schematic views illustrating an example of theband ply of a comparative example tire.

FIG. 41 is a schematic view illustrating a conventional band ply.

FIG. 42 is an enlarged sectional view of an end portion of the beltlayer thereof.

BEST MODES FOR CARRYING OUT THE INVENTION

An embodiment of this basic invention will be described, giving thefirst invention as an example hereinafter.

FIG. 1 is a meridian section of a pneumatic radial tire of the presentembodiment. In FIG. 1, a pneumatic radial tire 1 (referred to as thetire 1 hereinafter) has a carcass 6 which extends from a tread portion 2through a side wall portion 3 to a bead core 5 of a bead portion 4, abelt layer 7 arranged inside the tread 2 and outside the carcass 6 alongthe direction of the radius thereof, and a band layer 9 arranged outsidethe belt layer 7 along the direction of the radius thereof.

The carcass 6 is composed of one or more carcass plies, one carcass ply6A in the present example, wherein carcass cords are arranged at anangle of, for example, 75° to 90° to a tire equator C. This carcass ply6A has folded portions 6 b, which are each folded from the inside to theoutside around the bead core 5, at both ends of a body portion 6 aspreading over the bead cores 5 and 5, and further a bead apex rubber 8for reinforcing the bead, which extends in a tapered form from the beadcore 5 to the outside along the tire radius direction, is arrangedbetween the body portion 6 a and the folded portion 6 b.

As the carcass cords, polyester cords are adopted in the presentexample. Besides this, organic fiber cords made of nylon, rayon, aramideor the like maybe adopted. If necessary, steel cords may be adopted.

The belt layer 7 is formed in such a manner that two or more belt cords,two belt plies 7A and 7B in the present example, which are arranged atan angle of, for example, 15 to 45° to the tire equator C, areoverlapped in such a direction that the cords cross each other. The plywidth of the belt ply 7A which is inside along the radius direction ismade larger that of the outside belt ply 7B, whereby this ply width ismade up to the width BW of the belt layer 7. As the belt cords, steelcords are adopted in the present example. If necessary, however,high-modulus organic fiber cords made of polyethylene naphthalate (PEN),polyethylene terephthalate (PET), aromatic polyamide or the like may beused.

In the present embodiment, the band layer 9 is made of one full band ply9A covering almost all of the width of the belt layer 7 in order to keepthe dimensional stability of the tire high at the time of vulcanizationforming or use of the tire. The words “almost all of the width” meanthat the ply covers 95% or more of the width BW of the belt layer 7. Inthe present example, the width W of the full band ply 9A issubstantially equal to the width BW of the belt layer 7.

In the present description, the size of each of members or portions is avalue obtained by measurement in an unloaded state in which the tire 1is integrated with a regular rim and a regular internal pressure isapplied to the tire. The words “regular rim” is a rim specified for eachof tires in a standard system including a standard which the tires arebased on. For example, the regular rim is a standard rim according toJATMA, is a “design rim” according to TRA, or is a “measuring rim”according to TRTO. The words “regular internal pressure” is an airpressure specified for each of tires in a standard system including astandard which the tires are based on. The regular internal pressure isthe highest air pressure according to JATMA, is the maximum valuedescribed in Table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATIONPRESSURES” according to TRA, or is an “inflation pressure” according toETRTO. In the case that a tire is for a passenger car, the regularpressure is set to 180 KPa.

As illustrated in FIG. 2(A) and FIG. 2(B), which is a sectional viewthereof, the full band ply 9A is formed by winding a tape- and belt-formply 13, wherein one or more (for example, about 3 to 10) stretched andarranged band cords 11 are embedded in a topping rubber 12, spirally.The angle between this band ply 13 and the circumferential direction ofthe tire is set to 5 degrees or less. The full band ply 9A formed bysuch spiral winding of the belt-form ply 13 has the so-called jointlessstructure, which has no joint; therefore, the full band ply 9A servesfor superior uniformity of the tire and firm and sure restraint of thebelt layer 7. As illustrated in FIG. 2(B), in the belt-form ply 13, thethickness T (thickness from the outer face of the band cords 11, whichis shown by an imaginary line, to the outer face of the belt-form ply13) of the topping rubber 12 is preferably from 0.7 to 1.5 mm, morepreferably from 0.7 to 1.3 mm. In the present example, the belt-form ply13 whose width PW is about 10 mm is used.

When the belt-form ply 13 is spirally wound on the outside of the beltlayer 7, it is preferred for the uniformity thereof to perform thewinding in such a manner that adjacent side edges of the belt-form ply13 contact each other, as illustrated in FIG. 3(A). However, it ispossible to select the pitch P in the tire axial direction and adoptvarious winding manners, for example, the manner of separating the sideedges from each other and winding the ply, or the manner of overlappingthe side edges and winding the ply, as illustrated in FIGS. 3(B) and(C).

As the band cords 11, for example, organic fiber cords are preferablyused. In order to obtain a better effect of decreasing road noise,preferred are high-modulus organic fiber cords made of polyethylenenaphthalate (PEN), polyethylene terephthalate (PET), aromatic polyamide,polyparaphenylenebenzobisoxazole (PBO) or the like, and composite cordswherein two or more organic fiber filaments, made of PEN+aromaticpolyamide, aromatic polyamide+PBO or the like, are twisted. Morespecifically, preferred are organic fiber cords having a 2% modulus of100 (N/mm²) or more, preferably 12000 (N/mm²) or more.

In order to suppress deterioration in transit noise and rollingresistance, based on the use of such organic fiber cords having a highmodulus, at a minimum level, the elongation resistance value K of thefull band ply 9A, decoded by the following equation (1), is set withinthe range of 99 to 700 in the basic invention, and is set within therange of 99 to 334 in the first invention using a single full band ply.K=S×M×D/100  (1)wherein S represents the sectional area (unit: mm²) of each of the bandcords, M represents the modulus (unit: N/mm²) when the elongation ofeach of the band cords is 2%, and D represents the band cord arrangementdensity per cm of the width of the full band ply (unit: cord number/cm).The modulus M is a value measured according to JIS L1017. Thearrangement density D is a value obtained by dividing the number of theband cords arranged in the length P (cm) of one pitch of the spiralwinding, as illustrated in FIG. 3, by the pitch length P.

The sectional area S of the band cords 11 is preferably, for example,0.05 (mm²) or more, more preferably 0.08 (mm²) or more, and still morepreferably from 0.13 to 0.35 (mm²). If the sectional area S of the bandcords 11 is too small, it is necessary to make the 2% modulus of theband cords and/or the arrangement density, or the like remarkably largerin order to make the elongation resistance value K high. Conversely, ifthe sectional area S of the band cords 11 is too large, the formabilityof the tire tends to deteriorate.

The arrangement density D of the band cords is preferably, for example,from 5 to 20 (cord number/cm), more preferably from 6 to 18 (cordnumber/cm) and still more preferably from 7 to 17 (cord number/cm). Ifthe arrangement density D of the band cords 11 is too small, the 2%modulus of the band cords and/or the sectional area thereof tend to beremarkably large in order to make the elongation resistance value Khigh. As a result, the production costs of the tire increase, and thedurability of the tire deteriorates. Conversely, if the arrangementdensity D is too large, the rubber adhesion to the band cords 11deteriorates so that the durability of the tire may fall, and forexample, looseness tend to be caused.

The elongation resistance value K is a value representing an index ofthe resistance against elongation per unit width and unit length of thefull band ply 9A. As this value K is larger, the power of restrainingthe belt layer 7 is larger.

The inventors manufactured various tires whose elongation resistancevalue K was varied by way of trial and used the elongation resistancevalue K as a parameter to research relationships with road noise,transit noise, and rolling resistance (

:

K

RN, TN, RR

). As a result, the inventors have found out that when the elongationresistance value K is limited within a given range, the effect ofdecreasing road noise can be effectively exhibited while deteriorationin transit noise and rolling resistance is kept below a minimumtolerance limit.

FIG. 4 shows an example of the relationships with road noise, transitnoise, and rolling resistance using the elongation resistance value K asa parameter. This figure demonstrates that as the elongation resistancevalue K becomes larger, the road noise gets lower and the transit noiseand rolling resistance get worse. However, as is understood fromapproximation curves of the experimental values, as the elongationresistance value K gets larger, the degree (curve inclination) of thedecrease in the road noise tends to become smaller and the degree of thedeterioration in the transit noise and the rolling resistance tend tobecome higher.

Accordingly, by using the tire within such a range that the degree ofthe decrease in the road noise and the degree of the deterioration inthe transit noise and the rolling resistance do not yet start to changeabruptly, that is, the range of K≦334, the decrease in the road noiseand the suppression of the deterioration in the transit noise and therolling resistance can be most effectively attained.

If the elongation resistance value K is less than 99, the effect ofdecreasing the road noise is insufficient. Conversely, if the value K ismore than 334, in particular, the transit noise and the rollingresistance deteriorate abruptly. Accordingly, from the viewpoint of theeffect of decreasing the road noise, the elongation resistance value Kis preferably from 166 to 334, more preferably from 204 to 334, andstill more preferably from 298 to 334.

In the basic invention, (which may be referred to as the presentinvention), individual values of the sectional area S, the modulus M andthe arrangement density D are not particularly limited. The modulus M ispreferably 1000 N/mm² or more, more preferably 12000 N/mm² or more. Ifthis modulus M is too small, the sectional area S and the arrangementdensity D get large in order to make the elongation resistance value Khigh. As a result, the forming of the tire is apt to be difficult, andthe durability thereof is apt to deteriorate.

The sectional area S is preferably 0.05 mm² or more, more preferably0.08 mm² or more, and still more preferably from 0.13 to 0.35 mm². Ifthe sectional area S is too small, it is necessary to make the modulus Mand the arrangement density D large in order to make the elongationresistance value K high. As a result, raw material is not easilyselected. Moreover, the same inconveniences as described above arecaused. Conversely, if the sectional area S is too large, theformability of the tire tends to fall.

The arrangement density D is preferably from 4 to 16 (cord number/cm),more preferably from 7 to 13 (cord number/cm). If the arrangementdensity D is too small, the sectional area S and the modulus M get largein order to make the elongation resistance value K high. Thus, theproduction costs of the tire increase, and the durability of the tiredeteriorates. Conversely, if the arrangement density D is too large, therubber adhesion deteriorates so that the durability of the tire tends tofall.

Next, about the full band ply 9A, the elongation resistance value K canbe substantially constant over the entire width of the full band ply 9A,as attained in the present example. Within the above-mentioned range of99 to 334, the elongation resistance value Kc of the band central areaYc near the tire equator C can be made different from the elongationresistance value Kc of band outside areas Ys outside it. In particular,in the case of Kc<Ks, transit noise can be improved while keepingabove-mentioned effect of suppressing deterioration in road noise androlling resistance.

The band central area Yc means a width area corresponding to 20 to 80%of the width BW of the full band ply 9A, the center of the width areabeing the tire equator C. The areas outside it are referred to as theband outside areas Ys.

Means for setting the elongation resistance values to Kc<Ks are asfollows:

-   (1) The pitch P in the tire axial direction of the spiral winding of    the belt-form ply 13 in the band central area Yc is made larger than    the pitch P of the spiral pitch in the band outside areas Ys, and-   (2) The band cords, the number of which is j, are cut off from the    belt-form ply 13 in the band central area Yc.

In this way, the arrangement density D can be changed. In either case,at least the band cords 11 in the band central area Yc are continuous tothe band cords 11 in the band outside areas Ys.

The means (2) of these means can be preferably carried out from theviewpoints of the uniformity of the tire, stability of the tire shape,productivity, and so on since the cord angle of the band cords 11 doesnot change between the band central area Yc and the band outside areasYs.

This band layer 9 is advantageous for transit noise since the band layer9 relieves the rigidity of the band central area Yc to make envelopingproperty high. For this purpose, the elongation resistance value Kc ofthe band central area Yc is preferably 0.9 time or less the elongationresistance value Ks of the band outside areas Ys. For this purpose, thenumber j of the band cords which should be cut is set to 0.05 time ormore and 0.5 time or less, preferably 0.08 to 0.20 time the number J ofthe band cords 11 of the belt-form ply 13.

However, in the case that the elongation resistance value Kc isexcessively lowered, the band-restraining power decreases so that thetread surface in the band central area Yc becomes round. As a result,change in the tire shape gets large when the tire contacts the ground.Therefore, this case is disadvantageous for the rolling resistance.Thus, the elongation resistance value Kc is preferably 0.5 time or morethe elongation resistance value Ks, as described above. Accordingly, thenumber j is set to 0.5 time or less, preferably 0.2 time or less thenumber J.

(The second Invention)

About the second invention in the basic invention, an embodiment thereofwill be described.

The second invention has the same structure as the pneumatic tire of thefirst invention except the band layer 9. Thus, description thereon isomitted.

The band layer 9 of the second invention is composed of a pair of rightand left edge band plies 9B and 9B covering both ends of the belt layer7. This is because the weight of the edge band plies 9B is smaller thanthat of the full band ply covering the whole of the belt layer 7 andfurther deterioration in transit noise can be suppressed at a low levelwhile exhibiting the effect of decreasing road noise at substantiallythe same level. Additionally, the edge band ply 9B is arranged in such amanner that the outer end along the tire axial direction issubstantially consistent with the outer ends of the broad belt plies 7A.

The band layer 9 has the same structure as in the first invention. Forexample, the edge band ply 9B is formed by winding the belt-form ply 13spirally along the tire circumferential direction. Thus, description onthe same structure as in the band layer of the first invention is inprinciple omitted herein.

In order to suppress deterioration in transit noise by using suchhigh-modulus organic fiber cords as much as possible, the band layer 9is composed of the edge band plies 9B and 9B, and about the elongationresistance value K of the edge band ply 9B and the width ratio of theedge band ply width Wb to the belt layer width WB (Wb/WB), the edge bandply 9B is regulated as follows:

-   (1) the elongation resistance value K is set within the range of 120    or more and less than 246 and further the width ratio Wb/WB is set    within the range of 0.2 or more and 0.5 or less,-   (2) the elongation resistance value K is set within the range of 246    or more and less than 276 and further the width ratio Wb/WB is set    within the range of more than 0 and 0.5 or less, or-   (3) the elongation resistance value K is set within the range of 276    or more and 450 or less and further the width ratio Wb/WB is set    within the range of more than 0 and 0.41 or less.

The present embodiment embraces a case in which the width ratio Wb/WB is0.5, that is, the right and left edge band plies 9B and 9B substantiallycontact each other on the tire equator C, but is clearly distinguishedfrom ordinary full band plies wherein band cords are continuous from oneend thereof to the other end.

The inventors made various tires having different elongation resistancevalues K by way of trial, and researched effect on roads noise andtransit noise when the elongation resistance value K and the width ratioWb/WB were changed, respectively. The results are shown in FIGS. 6 and7.

The elongation resistance value K of the trial tires was plotted alongthe x axis, the width ratio Wb/WB thereof was plotted along the y axis,and the road noise at this time was plotted along the z axis. FIG. 6 isa bird's eye view obtained by viewing, from the z axis direction, athree-dimensional relationship between the elongation resistance valueK, the width ratio Wb/WB and the road noise, which relationship wasobtained from the above-mentioned plotting. Curves in this graphcorrespond to contour lines of the road noise presumed from therespective plotted values. About the road noise, the standard thereof isa noise level (dB) of a 250-Hz band of Comparative Example 1 (an edgeband ply made of nylon cords (elongation resistance value K: 80 N′ cordnumber/cm, width ratio Wb/WB: 0.5)) in the second invention, which levelis measured in a road noise test described in the column [Examples],which will be described later, and the road noise is represented by achange amount from this standard. Minus representations mean good caseswherein the road noise is smaller than those of Comparative Example 1.

As is evident from FIG. 6, in an area wherein the elongation resistancevalue K is large and the width ratio Wb/WB is large, the effect ofdecreasing the road noise is high. Thus, in an area Y1 shown by slantinglines, that is,

-   (a) the scope wherein the elongation resistance value K is 120 or    more and less than 246 and the width ratio Wb/WB is 0.2 or more and    0.5 or less, and-   (b) the scope wherein the elongation resistance value K is 246 or    more and 450 or less and the width ratio Wb/WB is more than 0 and    0.5 or less,

a decreasing effect of at least −0.3 dB or more can be ensured.

The elongation resistance value K of the trial tires was plotted alongthe x axis, the width ratio Wb/WB thereof was plotted along the y axis,and the transit noise at this time was plotted along the z axis. FIG. 7is a bird's eye view obtained by viewing, from the z axis direction, athree-dimensional relationship between the elongation resistance valueK, the width ratio Wb/WB and the transit noise, which relationship wasobtained from the above-mentioned plotting. Curves in this graphcorrespond to contour lines of the transit noise presumed from therespective plotted values. About the transit noise, in the same way thestandard thereof is a maximum level dB (A) of the transit noise of theabove-mentioned Comparative Example 1, which level is measured in thetransit noise test described in the column [Examples], which will bedescribed later, and the road noise is represented by a change amountfrom this standard. Minus representations mean good cases wherein theroad noise is smaller than those of Comparative Example 1.

As is evident from FIG. 7, in an area wherein the elongation resistancevalue K is large and the width ratio Wb/WB is approximate to 0.5, thetransit noise tends to deteriorate largely. Thus, it has been provedthat in an area Y2 shown by slanting lines, that is,

-   (c) the scope wherein the elongation resistance value K is 276 or    more and 450 or less and further the width ratio Wb/WB is more than    0.41 and 0.5 or less,

the road noise and the transit noise are not easily made compatible evenin the case of the structure using the edge band ply 9B.

In other words, this means that in the area wherein the area Y2 isdeleted from the area Y1, that is, in the above-mentioned areas (1), (2)and (3), the road noise and the transit noise can be made compatible.From this fact, the present invention has been found out.

However, the following has been proved from results of furtherresearches made by the inventors: in the structure using the edge bandply 9B, a difference in the rigidity between a tread shoulder portionwherein the edge band ply 9B is arranged and a tread crown portioninside it becomes large, so that slip is easily caused when the treadcontacts the ground; and the rolling resistance may deteriorate sincethe tread crown portion is made round so that the change amount of thetread gets large when the tread contacts the ground.

Thus, in the same way as described above the inventors researched effecton the rolling resistance when the elongation resistance value K and thewidth ratio Wb/WB were changed, respectively. As a result, as shown inFIG. 8, it has been proved that in the case that the width ratio Wb/WBis approximately 0.3 or any value near this center value 0.3, which caseis general for edge band plies, the rolling resistance tends to getworse as the elongation resistance value K gets larger.

Accordingly, it has been proved that in an area Y3 shown by slantinglines, that is,

-   (d) the scope wherein the elongation resistance value K is 120 or    more and less than 246 and further the width ratio Wb/WB is more    than 0.2 and less than 0.41, and-   (e) the scope wherein the elongation resistance value K is 246 or    more and 450 or less and further the width ratio Wb/WB is more than    0.14 and 0.5 or less,

the road noise and the rolling resistance are not easily made compatibleon the basis of the structure of the edge band ply 9B.

Therefore, in particular, in the area wherein the areas Y2 and Y3 aredeleted from the area Y1, that is,

-   (4) the scope wherein the elongation resistance value K is 120 or    more and less than 246 and further the width ratio Wb/WB is 0.41 or    more and 0.5 or less, or-   (5) the scope wherein the elongation resistance value K is 246 or    more and 450 or less and further the width ratio Wb/WB is more than    0 and 0.14 or less,

the road noise, the transit noise and the rolling resistance can be madecompatible.

(The Third Invention)

The third invention will be described giving an embodiment thereof as anexample.

The third invention has the same structure as the pneumatic tire of thefirst invention except the band layer 9. Thus, description on thestructures other than the band layer is in principle omitted.

In the third invention, as illustrated in FIG. 9, the band layer 9 iscomposed of one full band ply 9A covering almost all of the width of thebelt layer 7 and both-side edge band plies 9B and 9B at both ends of thebelt layer 7 and outside it. The width W of the full band ply 9A issubstantially equal to the width WB of the belt layer 7. This case isexemplified. In the present embodiment, shown is a form in which thefull band ply 9A is arranged inwards along the tire radius direction andthe edge band ply 9B is arranged outwards along the tire radiusdirection. Even if the band ply 9A and 9B are overlapped reversely, thesame effects and advantages can be obtained.

The band layer 9 also has the same structure as in the first invention.For example, in the same way as in the first invention, the band ply 9Ais formed in such a manner that the angle thereof with respect to thetire circumferential direction is set to 5 degrees or less. In thisthird invention, by setting the elongation resistance value K of each ofthe full band ply 9A and the edge band ply 9B in a range of 110–386,road noise, transit noise and rolling resistance can be made compatible.

The inventors made many tires (size: radial tires for passenger cars of195/65R15 91H), wherein the elongation resistance values K and thewidths wb in the tire axial direction of the edge band ply 9B werevaried, by way of trial, and researched effects thereof on roads noise,transit noise and rolling resistance.

FIG. 11 shows an example thereof. The elongation resistance value K wasplotted along the transverse axis (x axis), the width ratio Wb/WBbetween the width Wb of the edge band ply 9B and the width WB of thebelt layer was plotted along the vertical axis (y axis), and the roadnoise at this time was plotted along the z axis, which is perpendicularto the paper surface. A three-dimensional relationship between theelongation resistance value K, the width ratio Wb/WB and the road noiseis shown as a bird's eye view, viewed from the z axis direction. Curvesin this graph correspond to contour lines of the road noise presumedfrom the respective plotted values.

Each of the sample tires was fitted to all wheels of a domestic FFpassenger car (displacement volume: 2000 cc) with rims (15×6 JJ) at aninternal pressure of 200 kPa. The car was traveled at a speed of 60km/hour on a smooth road surface. At a driver's sheet left-ear position,the noise level (dB) of a 250-Hz band of a ⅓ octave was measured. Thelevel is represented as a change amount of the noise level, using thetire of Comparative Example 1 in the third invention as a standard.Accordingly, minus representations mean good cases wherein the roadnoise is smaller than those of Comparative Example 1. The tire ofComparative Example 1 in the third invention is a tire having one fullband ply composed of nylon cords, and has a elongation resistance valueK of 80 (N′ cord number/cm) and a width ratio (Wb/WB) of 0.

The width ratio (Wb/WB) is changed from 0 to 0.5. The case that thewidth ratio (Wb/WB) is 0 means an embodiment wherein no edge band ply 9Bis present and the band layer 9 is made of the single full band ply 9A.This is an embodiment of the pneumatic radial tire recited in claim 1.In the case that the width ratio (Wb/WB) is 0.5, the right and left edgeband plies 9B and 9B substantially contact each other on the tireequator C. Apparently, it looks that the band layer 9 is composed of twofull band plies 9A. In this embodiment, however, its band cords are notcontinuous on the tire equator. Therefore, this embodiment is differentfrom an embodiment having two full band plies in the power ofrestraining the belt layer 7, and so on. Thus, they are clearlydistinguished from each other in structure.

As illustrated in FIG. 11, in an area wherein the elongation resistancevalue K (unit: N′ cord number/cm) is from 110 to 386 and the width ratio(Wb/WB) is from 0 to 0.5 (hereinafter referred to as the “area 1”), roadnoise is superior to those of Comparative Example 1 made of nylon bands.As the elongation resistance value K is larger, the effect of decreasingthe road noise is larger. This would be because by increasing theelongation resistance value K of the band ply, the effect of suppressingthe vibration of the belt layer 7 gets large. It can be verified that inthe case of the tires having the same elongation resistance value K, thetire having a larger width ratio (Wb/WB) is more profitable for the roadnoise.

The elongation resistance value K was plotted along the transverse axis(x axis), the width ratio Wb/WB between the width Wb of the edge bandply 9B and the width WB of the belt layer was plotted along the verticalaxis (y axis), and the rolling resistance at this time was plotted alongthe z axis, which is perpendicular to the paper surface. FIG. 12 is abird's eye view obtained by viewing, from the z axis direction, athree-dimensional relationship between the elongation resistance valueK, the width ratio Wb/WB and the rolling resistance, which relationshipwas obtained from the above-mentioned plotting. Curves in this graphcorrespond to contour lines of the rolling resistance presumed from therespective plotted values.

The rolling resistance is obtained by measuring the rolling resistancevalue of each of the tires with a rolling resistance tester under thefollowing conditions: rim: 15×6 jj, internal pressure: 230 kPa, load:4.0 kN, and speed: 80 km/h, and then dividing this by the load. Theevaluation is represented as a change amount, using the ComparativeExample 1 as a standard. Accordingly, plus representations mean rollingresistance values increased (deteriorated) from the Comparative Example1 (in the third invention). Conversely, minus representations mean goodcases wherein the rolling resistance is smaller than the ComparativeExample 1.

Surprisingly, FIG. 12 demonstrates that in the area wherein the widthratio (Wb/WB) is from about 0.2 to 0.3, the rolling resistance locallydeteriorates. This deterioration in the rolling resistance is remarkablewhen the elongation resistance value K is about 280 (N′ cord number/cm)or more. As a result of inventor's analysis, causes for this can bepresumed as follows: when the width ratio (Wb/WB) of the edge band ply9B is set to about 0.2 to 0.3, the tread surface curvature radius of thecentral area between the edge band plies becomes locally small so thatthe ground pressure becomes uneven. This is also based on the resultthat when the elongation resistance value K is set to 170 or less sothat the power of restraining the belt layer 7 is relieved,deterioration in the rolling resistance is little. When the elongationresistance value K is set within this range, the deterioration in therolling resistance gets little to a negligible degree throughout therange that the width ratio (Wb/WB) is from 0 to 0.5. Accordingly, as apreferred combination for suppressing road noise while suppressingdeterioration in the rolling resistance, the width ratio (Wb/WB) can beset to 0 to 0.5 or less, more preferably more than 0 and 0.5 or less inthe case that the elongation resistance value K is 110 or more and 170or less.

Furthermore, from FIG. 12, in the range that the width ratio (Wb/WB) isfrom 0.47 to 0.50, the rolling resistance tends to be improved ratherthan deterioration in the rolling resistance is small. This would bebased on the matter that the tread surface is kept flat over a widescope by the broad edge band plies 9B. It is also proved that when thewidth ratio (Wb/WB) is set within this range, good results are obtainedin the range that the elongation resistance value K is from 110 to 386.Accordingly, as another combination for suppressing road noise whilesuppressing deterioration in the rolling resistance, the width ratio(Wb/WB) can be set to 0.47 or more and 0.50 or less in the case that theelongation resistance value K is 110 or more and 386 or less.

Furthermore, from FIG. 12, in the range that the width ratio (Wb/WB) is0.07 or less, the rolling resistance tends to be improved rather thandeterioration in the rolling resistance is small in the same manner.This would be based on the matter that the tread surface is kept flatover a wide scope by the markedly slender edge band plies 9B. It is alsoproved that when the width ratio (Wb/WB) is set within this range, goodresults are obtained in the range that the elongation resistance value Kis from 110 to 280. Accordingly, as a further preferred combination forsuppressing road noise while suppressing deterioration in the rollingresistance, the width ratio (Wb/WB) can be set to 0 to 0.07, morepreferably more than 0 and 0.07 or less in the case that the elongationresistance value K is 110 or more and 280 or less.

When these areas are put together, the following areas in FIG. 12 arepreferred in an embodiment having an edge band ply:

-   a) in the case that the elongation resistance value K is 110 or more    and less than 170, the width ratio (Wb/WB) is more than 0 and 0.5 or    less (hereinafter referred to as the “area 2”),-   b) in the case that the elongation resistance value K is 170 or more    and 280 or less,    -   b1) an area wherein the width ratio (Wb/WB) is more than 0 and        0.07 or less (hereinafter referred to as the “area 3”),    -   b2) an area wherein the width ratio (Wb/WB) is 0.47 or more and        0.5 or less (hereinafter referred to as the “area 4”), and-   c) in the case that the elongation resistance value K is more than    280 and 386 or less, the width ratio (Wb/WB) is 0.47 or more and 0.5    or less (hereinafter referred to as the “area 5”).

The elongation resistance value K was plotted along the x axis, thewidth ratio between the width Wb of the edge band ply 9B and the widthWB of the belt layer (Wb/WB) was plotted along the y axis, and thetransit noise at this time was plotted along the z axis perpendicular tothe paper surface. FIG. 13 is a bird's eye view obtained by viewing,from the z axis direction, a three-dimensional relationship between theelongation resistance value K, the width ratio (Wb/WB) and the transitnoise, which relationship was obtained from the above-mentionedplotting. Curves in this graph correspond to contour lines of thetransit noise presumed from the respective plotted values.

The transit noise is according to an actual car coasting test prescribedin JASO/C/606. A car was caused to coast on a straight test course(asphalt road surface) at a distance of 50 m at a transit speed of 53km/hour, and further in the middle point of the course, the maximumlevel dB(A) of transit noises was measured with a fixed microphone setat a position 7.5 m sideway from the central line of the traveling and1.2 m apart from the road surface. The transit noise is represented as achange amount of the noise level, using the Comparative Example 1 as astandard. Accordingly, minus representations mean good values, which arevalues of the transit noise decreased from the Comparative Example 1.

According to FIG. 13, it can be understood that when the elongationresistance value K and the width ratio (Wb/WB) are increased to improvethe power of restraining the belt layer, the transit noise deteriorates.Specifically, in the case that the elongation resistance value K is 340or more, the width ratio (Wb/WB) ranges from 0.27 to 0.50 and ismarkedly bad. In the case that the width ratio (Wb/WB) is more than0.40, the transit noise deteriorates remarkably when the elongationresistance value K is more than 280. Accordingly, in order to suppresslarge deterioration in the transit noise, it is advisable to decide theelongation resistance value K and the width ratio (Wb/WB) from scopesother than this scope. Specifically, the following ranges are selected:

-   d) in the case that the elongation resistance value K is 110 or more    and 280 or less, the width ratio (Wb/WB) is more than 0 and 0.5 or    less (hereinafter referred to as the “area 6”),-   e) in the case that the elongation resistance value K is more than    280 and less than 340, the width ratio (Wb/WB) is more than 0 and    0.4 or less (hereinafter referred to as the “area 7”), and-   f) in the case that the elongation resistance value K is 340 or more    and 386 or less, the width ratio (Wb/WB) is more than 0 and less    than 0.28 (hereinafter referred to as the “area 8”).

In order to obtain a most preferred pneumatic radial tire making itpossible to decrease road noise while suppressing deterioration in thetransit noise and the rolling resistance at a lowest level, it issufficient to decide portions where the areas 1 to 8 overlap. The areasare as follows:

-   g) in the case that the elongation resistance value K is 110 or more    and 170 or less, the width ratio (Wb/WB) is more than 0 and 0.5 or    less, and-   h) in the case that the elongation resistance value K is more than    170 and 280 or less, the width ratio (Wb/WB) is more than 0 and 0.07    or less, or 0.47 or more and 0.50 or less.    (The Invention about Density Change)

In the invention illustrated in FIGS. 14 to 20, a band ply compriseshigh density portions 10 a and low density portions 10 b, whereby roadnoise can be decreased while suppressing deterioration in transit noiseeffectively at a lowest level. As described above, this invention can beadopted for the first and third inventions within the scope that theelongation resistance values K overlap.

As illustrated in FIG. 14, a band layer 9 is made of one band ply 9covering almost all of the width of a belt layer 7, and the following isillustrated: the band ply 9 formed by winding one belt-form ply 13continuously and spirally from one end 7 e of the belt layer 7 to theother end 7 e. In this way, joints of the ply are reduced so that theuniformity of the tire can be improved.

As illustrated in FIGS. 14 and 15, the band ply 9 comprises high densityportions 10 a constituting both outside portions SH and SH along thetire axial direction, wherein the winding pitch P1 of the belt-form ply13 is 1.0 time or less the width PW of the belt-form ply; and lowdensity portions 10 b arranged between the high density portions 10 a,wherein the winding pitches P2, P3 and P4 of the belt-form ply 13 arefrom 1.2 to 2.6 times the width PW of the belt-form ply. The windingpitches are each the shift amount of the ply along the tire axialdirection when the ply 13 makes a round of the tire in thecircumferential direction.

As the high density portion 10 a in the present example, the followingembodiment is illustrated: an embodiment wherein the winding pitch P1 ofthe belt-form ply 13 is set to 1.0 time the width PW of the belt-formply 13 and the ply is spirally wound in such a manner that side edges 13e of the belt-form ply 13 adjacent to each other along the tire axialdirection contact each other. The high density portions 10 a make highthe arrangement density of band cords 11 in the two outside portions SHof the belt layer 7, and further makes smaller the angle θ1 of the bandcords 11 to the tire circumferential direction, as illustrated in FIG.16. Specifically, the angle θ1 of the band cords 11 to the tirecircumferential direction, in the high density portions 10 a, can be setto about 0.1 to 0.4 degree. By synergetic effects of these, the highdensity portions 10 a have higher restraining power in the two outsideportions SH of the belt layer 7, and can decrease road noiseeffectively.

The width BW1 of the high density portions 10 a along the tire axialdirection is not particularly limited. However, if the width is toosmall, the effect of tightening the outside portions SH of the beltlayer 7 with high restraining power to decrease road noise tends to getsmall. Conversely, if the width is too large, high restraining power isliable to be given to the tread central portion so that the level oftransit noise tends to deteriorate. From various experiments in light ofsuch a viewpoint, the width BW1 of the high density portions 10 a alongthe tire axial direction is desirably from 7 to 34% of the maximum widthW of the belt layer 7 along the tire axial direction, more preferablyfrom 14 to 27% thereof, and particularly preferably from 17 to 23%thereof.

In the low density portions 10 b, the winding pitch of the belt-form ply13 is made larger than the winding pitch of the high density portions 10a along the tire axial direction, and separating portions 14 are formedbetween the belt-form ply portions 13 and 13 adjacent along the tireaxial direction. In the separating portions 14, side edges 13 e and 13 ethereof are separated from each other. In these low density portions 10b, the arrangement density of the band cords is small, and further theangle θ2 of the band cords 11 to the tire circumferential direction canbe set to larger than that in the high density 10 a, as illustrated inFIG. 16. More specifically, the angle can be set to an angle θ2 of aboutnot more than 0.5 to 2.0 degrees to the tire circumferential direction.By synergetic effects of these, the low density portions 10 b makes itsrestraining power weak in the central portion Cr of the belt layer 7 soas to suppress deterioration in transit noise. In the present example,shown is an example wherein the low density portions 10 b having a widthBW2 are formed over the whole areas between the high density portions 10a and 10 a. In order to prevent deterioration in the transit noise, itcan be considered that no band ply is formed in the central portion Cr,as illustrated in FIG. 20. In this case, however, the rolling resistancetends to deteriorate largely. Thus, the case is not preferred.

As illustrated in FIG. 15, in the present embodiment, agradually-increasing portion 15, wherein the winding pitch increasesgradually towards the tire equator C, is formed in the low densityportions 10 b. That is, as illustrated in FIG. 15, in thegradually-increasing portion 15 the winding pitch thereof satisfies therelationship of P2<P3<P4. For example, when the belt-form ply 13 iswound, the winding pitch can be changed by a single winding step in theportion wherein the high density portion 10 a is transited to the lowdensity portions 10 b. In such a case, for example, large restrainingpower in the high density portion 10 a decreases suddenly in theboundary portion with the low density portions 10 b, so that the loss ofthe road noise decreasing effect is readily generated. On the otherhand, for example, the gradually-increasing portion 15, wherein thewinding pitch increases gradually towards the tire equator C, is formedin the low density portions 10 b of the band ply 10, whereby therestraining power in the tread central portion Cr is lowered to preventdeterioration in the transit noise. At the same time, sudden fall in therestraining power on the side of the outside portion SH is prevented.Thus, the road noise decreasing effect can be exhibited at a maximumlevel.

The embodiment wherein this gradually-increasing portion 15 is formed inthe low density portions 10 b is illustrated. However, as illustrated inFIG. 17, a gradually-increasing portion 15 wherein the winding pitchincreases gradually (P1<P2<P3<P4) towards the tire equator can also beformed in the high density portion 10 a. Desirably, the restrainingpower is gradually changed by limiting the increase rate of the windingpitch in this gradually-increasing portion 15, for example, to about 5to 55%, more preferably about 15 to 45%. In this way, the road noisedecreasing effect and the effect of preventing deterioration in thetransit noise can be improved with a good balance.

In the case of the tire wherein its band ply has the high densityportions 10 a and the low density portions 10 b, the elongationresistance value K (unit: N′ cord number/cm) is desirably set to 130 to700, more preferably 166 to 467, still more preferably 213 to 467, andparticularly preferably 247 to 334. By organic combination of theabove-mentioned structure of the band ply 10 with the belt-form ply 13having a limited elongation resistance value K, road noise can beeffectively decreased without generating remarkable deterioration in thetransit noise and the rolling resistance.

In the case that the elongation resistance value K of the belt-form ply13 is smaller than 130 (N′ cord number/cm), the power of restraining thebelt layer 7 gets small so that road noise cannot be sufficientlydecreased. Conversely, in the case that the elongation resistance valueK is more than 700 (N′ cord number/cm), the sectional area of the bandcords 11, the arrangement density of the band cords or the 2% modulus ofthe band cords 11 gets markedly large so that the shaping of the tireitself becomes difficult. In addition, the restraining power in the lowdensity portions 10 b is made excessively high to deteriorate noiseexcessively.

FIG. 18(A) illustrates a case in which the band layer 9 is composed of afull band ply 10A, and an edge band ply 10B covering only a high densityportion 10 a of this full band ply 10A, and FIG. 18(B) illustrates acase in which low density portions 10 b are also made of two layers.

(The Invention about the Overlap of a Band with a Belt Layer)

Furthermore, in a band ply, the elongation resistance value K (unit: N′cord number/cm) is set to 166 to 467 and further a winding terminalportion cl constituting a one-circumference portion ahead of the windingterminal of a belt c is formed at a position where it does not directlycontact the outer end of the belt layer in the tire axial direction.This can be applied to the first to the third inventions if this is in aform which can be adopted for the first to the third inventions.

This intends to prevent a rubber exfoliation j generated between thewinding terminal portion c1, which constitutes a one-circumferenceportion ahead of the winding terminal of the belt-form ply c, and thebelt-form ply c2 wound inside it, as illustrated in FIGS. 41 and 42.(Such an exfoliation damage may be referred to as a “belt edgelooseness” hereinafter.) It has been made evident that this rubberexfoliation j is formed as follows: exfoliation starts from amicroscopic rubber exfoliated portion a1 generated near outer end be ofa belt layer b, which has a poor adhesion to the rubber, and then theexfoliation grows between the winding terminal portion c1 of thebelt-form ply c, at which restraining power is readily lowered since theend is free, and a belt-form ply c2 so as to reach an outer faceposition a2 of the band ply f.

That is, in this “invention of the overlap of a band with a belt layer”,the elongation resistance value K (unit: N′ cord number/cm) of a bandply made of at least one layer is preferably set to 166 to 467. Thisinvention can be adopted in the first to the third inventions within thescope that the elongation resistance values K overlap, as describedabove. When the elongation resistance value K of the band ply 10 a issmaller than 166 (N′ cord number/cm), the road noise decreasing effectcannot be sufficiently obtained. Conversely, if the elongationresistance value K is more than 467 (N′ cord number/cm), the sectionalarea of the band cords, the number of the embedded band cords or the 2%modulus of the band cords gets markedly large so that the shaping of thetire is apt to become difficult. More preferably, the elongationresistance value K is set to 180 to 350 (N′ cord number/cm), morepreferably 220 to 300 (N′ cord number/cm).

For example, as illustrated in FIG. 23, the band ply 9A can be composedof a first ply piece 9 a and a second ply piece 9 b which have windingstarting ends 13 a of a belt-form ply 13 at each of outer ends 7 e 1 and7 e 2 of a belt layer 7, are spirally wound towards the tire equator,and further have winding terminal portions 13 be of the belt-form ply 13near the tire equator. The first and second ply pieces 9 a and 9 b canrestrain almost all of the belt layer 7.

When the band ply 9A is schematically illustrated, the winding startingends 13 a of the belt-form ply 13 are represented by black spots (●) andthe winding terminals 13 b are represented by arrows (→). As exemplifiedin FIG. 24, the winding starting end 13 a of the belt-form ply 13 of theband ply 9A is an end at which winging is started, and the windingterminal 13 be thereof is an end at which the winding is finished. Thewinding terminal portion 13 be is a one-circumference portion ahead ofthe winding terminal 13 b, and the winding starting end portion 13 a isa one-circumference portion after the winding starting end 13 a.

In the band ply 9A as illustrated in FIG. 23, the winding terminalportions 13 be of the belt-form ply 13 do not directly contact the outerends 7 e 1 and 7 e 2 of the belt layer 7. It is therefore possible toprevent microscopic cracks or the like, which are readily generated atthe outer ends 7 e 1 and 7 e 2 of the belt layer 7, from entering thewinding terminal portions 13 be of the belt-form ply 13, wherein rubberexfoliation is readily generated, and growing in the portions 13 be. Inshort, any belt edge looseness can be effectively prevented. The directcontact of the winding terminal portion 13 be with the outer end of thebelt layer 7 along the tire axial direction includes both of the casethat the outer end 7 e 2 (or 7 e 1) of the belt layer 7 is consistentwith the side edge of the winding terminal portion 13 be as illustratedin FIG. 25(A), and the case that the winding terminal portion 13 be goesacross the outer end 7 e 2 (or 7 e 1) of the belt layer 7 as illustratedin FIG. 25(B).

The winding starting end portions 13 a are positioned at the outer ends7 e 1 and 7 e 2 of the belt layer 7, respectively. As enlarged andillustrated in FIG. 26, about a winding starting end portion 13 aeincluding the winding starting end 13 a in the present example, at leastone part thereof is covered and tightened with the belt-form ply 13 f,which will be wound later, so as to make the power of restraining thebelt layer 7 high. As a result, it is possible to prevent microscopiccracks or the like generated at the outer end 7 e 1 of the belt layer 7from advancing between the winding starting end portion 13 ae and thenext belt-form ply 13 f. Particularly preferably, the overlap length Dof the winding starting end portion 13 ae with the next belt-form ply 13f is from 0.1 to 1.0 time, more preferably from 0.3 to 0.9 time, andstill more preferably from 0.6 to 0.8 time the width W1 of the belt-formply. The present example is an example wherein the outer side edge,along the tire axial direction, of the winding starting end portion 13ae is arranged along the outer end 7 e 1 of the belt layer 7.

In the belt layer 7, a good adhesion between the rubber and the beltcords is attained at positions besides the outer ends 7 e 1 and 7 e 2.Accordingly, the position of the winding starting end portion 13 ae ofthe belt-form ply 13 is not particularly limited if direct contactthereof with the outer ends 7 e 1 and 7 e 2 can be avoided.

The following will exemplify specific embodiments.

A band ply 9A illustrated in FIG. 27 can also be composed of a first plypiece 9 a and a second ply piece 9 b which have winding starting ends 13a of a belt-form ply 13 at respective outer ends 7 e 1 and 7 e 2 of abelt layer 7, and have winding terminal portions 13 be of the belt-formply 13 at shoulder portions. In this embodiment, the so-called edge bandply in a center-empty form, wherein the crown portion of the belt layer7 is not covered is formed. It is effective for decrease in road noiseto set the width of the ply piece 9 a or 9 b to at least 7% or more ofthe width WB of the belt layer 7.

A band ply 9A illustrated in FIG. 28 is composed of a first ply piece 9a and a second ply piece 9 b which respectively have winding startingends 13 a of a belt-form ply 13 near the tire equator, and are spirallywound therefrom towards outer ends 7 e 1 and 7 e 2 of a belt layer 7 andoutwards along the tire axial direction, turned again toward the tireequator without being interrupted at the outer ends 7 e 1 and 7 e 2 ofthe belt layer, and spirally wound, whereby winding terminal portions 13be are positioned at shoulder portions. In this band ply 9A, thebelt-form ply 13 overlaps with each other to be of two layers at theshoulder portions in substantially the same manner as in the combinationof a full band and edge bands. Therefore, the shoulder portions, whereinlifting is particularly readily generated during high-speed operation,is firmly restrained to make the high-speed durability high. In thecrown portion, the belt-form ply 13 has a monolayer structure, and thusdeterioration in comfortableness when persons rise in the car having thepresent tire can be suppressed as a lowest level.

A band ply 9A illustrated in FIG. 29 is based on the embodiment of FIG.28, but is composed of a first ply piece 9 a and a second ply piece 9 bwherein winding terminal portions 13 be of a belt-form ply 13 arepositioned near the tire equator. In this case, the belt-form plyoverlaps with each other to be of two layers over almost all of thewidth of a belt layer 7; therefore, the rigidity of the tread surface isuniformly made high and the road noise performance is regarded as moreimportant so as to be improved. In this point, the present band ply isfavorable (the structure of two full bands).

A band ply 9A illustrated in FIG. 30 is composed of a first ply piece 9a and a second ply piece 9 b. The respective ply pieces 9 a and 9 b arepositioned so that winding starting ends 13 a and 13 a of a belt-formply 13 are close to each other and approach one outer end 7 e 1 of abelt layer from the tire equator C. The second ply piece 9 b is spirallywound toward the other outer end 7 e 2 of the belt layer, further turnedat the outer end 7 e 2, and spirally wound again toward the tireequator. Moreover, the second ply piece 9 b has a winding terminalportion 13 be positioned in front of the tire equator C. On the otherhand, the first ply piece 9 a is spirally wound toward the one outer end7 e 1 of the belt layer, turned at the above-mentioned outer end 7 e 1,and spirally wound again toward the tire equator and outside the secondply piece 9 b. Moreover, the first ply piece 9 a is over the tireequator C so that the winding terminal portion 13 be is positionedclosely to the winding terminal portion of the second ply piece 9 b (thestructure of two full bands).

A band ply 9A illustrated in FIG. 31 is also composed of a first plypiece 9 a and a second ply piece 9 b. The respective ply pieces 9 a and9 b have winding starting ends 13 a and 13 a of a belt-form ply 13 nearouter ends 7 e 1 and 7 e 2 of a belt layer, and are spirally woundoutwards along the tire axial direction, turned at the respective outerends 7 e 1 and 7 e 2, and spirally wound again toward the tire equator.Moreover, the respective ply pieces 9 a and 9 b have winding terminalportions 13 be positioned near the tire equator C. In this way, astructure having one full band and one edge band is substantiallyformed.

A band ply 9A illustrated in FIG. 32 is also composed of a first plypiece 9 a and a second ply piece 9 b. The first ply piece 9 a has awinding starting end 13 a of a belt-form ply 13 near one outer end 7 e 1of a belt layer, and is spirally wound outwards along the tire axialdirection, turned at the outer end 7 e 1, and spirally wound againtoward the tire equator. Moreover, the first ply piece 9 a has a windingterminal portion 13 be positioned near the tire equator C. On the otherhand, the second ply piece 9 b has a winding starting end 13 a of thebelt-form ply 13 near the winding terminal portion 13 be of the firstply piece 9 a, and is spirally wound toward the other outer end 7 e 2 ofthe belt layer, turned at the outer end 7 e 2, and spirally wound againtoward the tire equator. Moreover, the second ply piece 9 b has awinding terminal portion 13 be positioned in front of the tire equatorC. In this way, a structure having one full band and one edge band issubstantially formed.

A band ply 9A illustrated in FIG. 33 has a winding starting end 13 a ofa belt-form ply 13 near one outer end 7 e 1 of a belt layer, and isspirally wound outwards along the tire axial direction, turned at theouter end 7 e 1, and spirally wound again toward the other outer end 7 e2 of the belt layer. Further, the band play 9A is turned at the outerend 7 e 2 and spirally wound again toward the tire equator. The band plypiece 9A has a winding terminal portion 13 be positioned in front of thetire equator C. In this way, a structure having one full band and oneedge band is substantially formed.

A band ply 9A illustrated in FIG. 34 has a winding starting end 13 a ofa belt-form ply 13 near the tire equator C, and is spirally wound towardone outer end 7 e 1 of a belt layer, turned at this outer end 7 e 1, andspirally wound again toward the other outer end 7 e 2 of the belt layer.The band ply piece 9A is again turned at this outer end 7 e 2, andspirally wound so that a winding terminal portion 13 be is positionednear the tire equator C. In this way, a structure having two full bandsis substantially formed.

FIGS. 35 to 37 illustrate band plies wherein a band layer 9 is made ofband cords of two kinds. A band ply 9A illustrated in FIG. 35 iscomposed of a first ply piece 9 a covering one shoulder portion of abelt layer 7, a second ply piece 9 b covering the other shoulderportion, and a third ply piece 9 c arranged between the first ply piece9 a and the second ply piece 9 b. Each of the first and second plypieces 9 a and 9 b has a winding terminal portion 13 be positioned atits inner end side along the tire axial direction. The third ply piece 9c is made of a belt-form ply using band cords 10 having a lower modulusthan band cords of the first and second ply pieces 9 a and 9 b.

A band ply 9A illustrated in FIG. 36 is based on the embodiment of FIG.35, but the third ply piece thereof is spirally wound from one outer end7 e 1 of a belt layer 7 to the other outer end 7 e 2. In thisembodiment, a winding terminal portion 13 be of the third belt ply isclose to an outer end 7 e 2 of the belt layer, but the second ply piecelies between these. Therefore, direct contact thereof can be prevented.A band ply 9A illustrated in FIG. 37 is based on the embodiment of FIG.36, but each of the first ply pieces 9 a and 9 b extends to the tireequator. When a band ply is composed of plural kinds, it is sufficientthat the band ply of at least one layer satisfies the elongationresistance value K.

FIG. 38 illustrates a further embodiment of the present invention.

In a band ply 9A of the present embodiment, a winding starting end 13 aof a belt-form ply is positioned outside one outer end 7 e 1 of a beltlayer 7 along the tire axial direction, and further the band ply 9A isspirally wound therefrom so that a winding terminal portion 13 be ispositioned outside the other outer end 7 e 2 of the belt layer along thetire axial direction.

In FIG. 39, the belt layer 7 is composed of a first belt ply 7A having alarge width along the tire axial direction, and a second belt ply 7Bwhich is arranged inside the first belt ply 7A in such a manner that thecenters thereof are consistent with each other, and which has a smallerwidth than that of the first belt ply 7A. This belt 7 can relieve stepsgenerated by ends of the respective belt plies by covering the end ofthe second belt ply with the first belt ply. In this way, ends which arestart points of the generation of belt edge looseness are reduced sothat the endurance can be made still higher.

According to this embodiment, in a band ply 9A a winding starting end 13a of a belt-form ply is positioned inside one outer end 7 e 1 of a beltlayer 7 along the tire axial direction, and further the band ply 9A isspirally wound therefrom so that a winding terminal portion 13 be ispositioned inside the other outer end 7 e 2 of the belt layer along thetire axial direction.

Embodiments will be described hereinafter.

(First Invention)

Tires having a tire size of 195/65R15 91H were made by way of trial onthe basis of the specifications of Tables 1, 2 and 3. The road noiseperformance, the transit noise performance and the rolling resistanceperformance of the respective sample tires were tested and compared.

The manner of the test is as follows.

(1) Road Noise Performance

Each of the sample tires was fitted to all wheels of a domestic FFpassenger car (displacement volume: 2000 cc) with rims (15×6 JJ) at aninternal pressure of 200 kPa. The car was traveled at a speed of 60km/hour on a smooth road surface. At a driver's sheet left-ear position,the noise level (dB) of a 250-Hz band of a ⅓ octave was measured. Thelevel is represented as a change amount of the noise level, usingComparative Example 1 as a standard. Accordingly, minus representationsmean road noise values decreased from Comparative Example 1.

(2) Transit Noise Performance

The transit noise was according to an actual car coasting testprescribed in JASO/C/606. A car was caused to coast on a straight testcourse (asphalt road surface) at a distance of 50 m at a transit speedof 53 km/hour, and further in the middle point of the course, themaximum level dB (A) of transit noises was measured with a fixedmicrophone set at a position 7.5 m sideway from the central line of thetraveling and 1.2 m apart from the road surface. The transit noise isrepresented as a change amount of the noise level, using ComparativeExample 1 as a standard. Accordingly, minus representations mean goodvalues, which are values of the transit noise decreased from theComparative Example 1.

(3) Rolling Resistance Performance

A rolling resistance tester was used to measure the rolling resistancevalue of each of the tires under the following conditions: rim: 15×6 JJ,internal pressure: 230 kPa, load: 4.0 kN, and speed: 80 km/h. Therolling resistance is represented as a change amount, using ComparativeExample 1 as a standard. Accordingly, plus representations mean rollingresistance values increased (deteriorated) from Comparative Example 1.

TABLE 1 Comparative Comparative Comparative Comparative Example 1Example 2 Example 3 Example 4 Example 1 Example 2 Example 3 Example 4Belt layer width BW <mm> 148 148 148 148 148 148 148 148 Band structure*1 1FB 1FB 1FB 1FB 1FB 1FB 1FB 1FB Ply width W <mm> 148 148 148 148 148148 148 148 Cord material *2 NYLON PEN PEN PEN PEN PEN PEN PEN Cordsectional area S <mm²> 0.2478 0.246 0.2456 0.1618 0.2456 0.2456 0.24560.2456 Cord modulus M <N/mm²> 3228 8657 11235 15230 11235 11235 1123511235 Cord arrangement density D <number/1 cm> 10 4 14 16 12 10 8 6Elongation resistance value K Central area Kc 80 85 386 394 331 276 221166 Outside area Ks 80 85 386 394 331 276 221 166 Number J of cords inthe belt-form ply 10 10 10 10 10 10 10 10 Number of the cords cut in thecentral area 0 0 0 0 0 0 0 0 Road noise performance <dB> 0.0 0.1 −5.2−5.3 −4.6 −3.4 −2.3 −1.3 Transit noise performance <dB(A)> 0.0 −0.1 0.91.0 0.3 0.3 0.1 0.0 Rolling resistance performance 0 0 7 8 6 4 2 1 *11FB represents one full band ply, and 1FB′ represents a full band plywherein a part of cords are cut in the central area of the ply. *2 PENmeans polyethylene-2,6-naphthalate.

TABLE 2 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10Example 11 Belt layer width BW <mm> 148 148 148 148 148 148 148 Bandstructure *1 1FB 1FB 1FB 1FB 1FB 1FB 1FB Ply width W <mm> 148 148 148148 148 148 148 Cord material *2 PEN PEN PEN PEN PEN PEN PEN Cordsectional area S <mm²> 0.2456 0.246 0.246 0.246 0.246 0.246 0.162 Cordmodulus M <N/mm²> 11235 13568 13568 8657 8657 8657 12590 Cordarrangement density D <number/1 cm> 4 10 4 14 10 8 10 Elongationresistance value K Central area Kc 110 334 134 298 213 170 204 Outsidearea Ks 110 334 134 298 213 170 204 Number J of cords in the belt-formply 10 10 10 10 10 10 10 Number of the cords cut in the central area 0 00 0 0 0 0 Road noise performance <dB> −0.3 −4.4 −0.7 −4.2 −2.3 −1.5 −2.2Transit noise performance <dB(A)> −0.1 0.5 −0.1 0.5 0.2 0.1 0.2 Rollingresistance performance 0 5 0 5 3 1 2 *1 1FB represents one full bandply, and 1FB′ means a full band ply wherein a part of cords are cut inthe central area of the ply. *2 PEN representspolyethylene-2,6-naphthalate.

TABLE 3 Example Example Example Example Example Comparative Comparative12 13 14 15 16 Example 5 Example 6 Belt layer width BW <mm> 148 148 148148 148 148 148 Band structure *1 1FB 1FB 1FB 1FB′ 1FB′ 1FB′ 1FB′ Plywidth W <mm> 148 148 148 148 148 148 148 Cord material *2 PEN PEN PENPEN PEN PEN PEN Cord sectional area S <mm²> 0.1618 0.1618 0.1618 0.16180.1618 0.1618 0.1618 Cord modulus M <N/mm²> 15230 15230 10001 1523015230 15230 15230 Cord arrangement density D <number/1 cm> 10 4 8 10 1010 10 Elongation resistance value K Central area Kc 246 99 129 172 12349 0 Outside area Ks 246 99 129 246 246 246 246 Number J of cords in thebelt-form ply 10 10 10 10 10 10 10 Number of the cords cut in thecentral area 0 0 0 3 5 8 10 Road noise performance <dB> −2.9 −0.2 −0.8−2.8 −2.7 −2.5 −2.4 Transit noise performance <dB(A)> 0.3 −0.1 0.0 0.0−0.1 −0.1 −0.2 Rolling resistance performance 3 0 1 4 4 5 6 *1 1FBrepresents one full band ply, and 1FB′ means a full band ply wherein apart of cords are cut in the central area of the ply. *2 PEN representspolyethylene-2,6-naphthalate.(Second Invention)

In the same way as in the first invention, tires having a tire size of195/65R15 91H were made by way of trial on the basis of thespecifications of Tables 4, 5, 6 and 7. Furthermore, the road noiseperformance, the transit noise performance and the rolling resistanceperformance of the respective sample tires were tested and compared inthe same way as in the first invention.

TABLE 4 Com- Com- Com- par- par- par- ative ative ative Exam- Exam-Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 2 ple 3 ple 7 ple 8 ple 9 ple 10Band structure *1 IEB IEB IEB IEB IEB IEB IEB IEB IEB IEB IEB IEB IEBCord material *2 NYL PEN PEN PEN PEN PEN PEN PEN PEN PEN PEN PEN PENSectional area S <mm²> 0.248 0.246 0.246 0.246 0.246 0.246 0.246 0.2460.246 0.246 0.246 0.246 0.246 Modulus M <N/mm²> 3228 11235 11235 1123511235 11235 11235 11235 11235 11235 11235 11235 11235 Arrangementdensity D 10 10 10 10 10 10 10 10 10 14 14 14 14 <number/1 cm>Elongation resistance 80 276 276 276 276 276 276 276 276 386 386 386 386value K Width ratio Wb/WB 50 7 14 20 27 34 41 47 50 7 14 20 27 <%> Roadnoise performance 0.0 −0.5 −1.3 −2.9 −2.9 −3.2 −3.2 −3.4 −3.4 −1.0 −2.5−5.1 −5.3 <dB> Transit noise 0.0 −0.3 −0.4 −0.4 −0.4 −0.4 −0.3 −0.1 0.0−0.5 −0.4 −0.4 −0.3 performance <dB(A)> Rolling resistance 0 −2 0 0 0 52 2 1 −1 0 8 12 performance *1 IEB represents a pair of edge band plies.*2 PEN represents polyethylene-2,6-naphthalate. (The belt layer width BWwas 148 mm in all of the examples.)

TABLE 5 Com- Com- Com- Com- par- par- par- par- ative ative ative ativeExam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam-Exam- ple 11 ple 12 ple 4 ple 5 ple 6 ple 13 ple 14 ple 15 ple 16 ple 17ple 18 ple 19 ple 7 Band structure *1 IEB IEB IEB IEB IEB IEB IEB IEBIEB IEB IEB IEB IEB Cord material *2 PEN PEN PEN PEN PEN PEN PEN PEN PENPEN PEN PEN PEN Sectional area S <mm²> 0.246 0.246 0.246 0.246 0.2460.246 0.246 0.246 0.246 0.162 0.162 0.162 0.162 Modulus M <N/mm²> 1123511235 11235 11235 11235 11235 11235 11235 11235 12590 12590 12590 12590Arrangement density D 14 14 14 14 6 6 6 6 6 16 16 16 16 <number/1 cm>Elongation resistance 386 386 386 386 166 166 166 166 166 326 326 326326 value K Width ratio Wb/WB 34 41 47 50 7 20 34 47 50 7 20 34 47 <%>Road noise performance −5.5 −5.7 −5.9 −5.9 0.3 −0.9 −1.0 −1.3 −1.3 −0.8−4.4 −4.6 −4.9 <dB> Transit noise −0.2 −0.1 0.3 0.5 −0.4 −0.4 −0.4 −0.4−0.2 −0.4 −0.4 −0.3 0.4 performance <dB(A)> Rolling resistance 9 8 7 6−3 1 0 −1 −1 0 7 7 6 performance *1 IEB represents a pair of edge bandplies. *2 PEN represents polyethylene-2,6-naphthalate. (The belt layerwidth BW was 148 mm in all of the examples.)

TABLE 6 Com- Com- Com- Com- Com- Com- Com- par- par- par- par- par- par-par- ative ative ative ative ative ative ative Exam- Exam- Exam- Exam-Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 8 ple 9 ple 10ple 20 ple 21 ple 22 ple 23 ple 24 ple 25 ple 11 ple 12 ple 13 ple 14Band structure *1 IEB IEB IEB IEB IEB IEB IEB IEB IEB IEB IEB IEB IEBCord material *2 PEN PEN PEN PEN PEN PEN PEN PEN PEN PEN PEN PEN PENSectional area S <mm²> 0.162 0.162 0.162 0.162 0.162 0.162 0.162 0.1620.162 0.162 0.162 0.162 0.162 Modulus M <N/mm²> 12590 12590 12590 1259012590 12590 12590 12590 12590 12590 12590 12590 12590 Arrangementdensity D 16 6 6 6 6 6 6 6 6 4 4 4 4 <number/1 cm> Elongation resistance326 122 122 122 122 122 122 122 122 81 81 81 81 value K Width ratioWb/WB 50 7 14 20 27 34 41 47 50 7 20 34 47 <%> Road noise performance−5.0 0.7 0.3 −0.4 −0.4 −0.4 −0.5 −0.6 −0.7 1.1 0.3 0.2 0.1 <dB> Transitnoise 0.5 −0.4 −0.4 −0.5 −0.4 −0.5 −0.4 −0.4 −0.3 −0.5 −0.4 −0.5 −0.5performance <dB(A)> Rolling resistance 4 −3 −1 0 −1 −1 −2 −2 −2 −3 −2 −2−2 performance *1 IEB represents a pair of edge band plies. *2 PENrepresents polyethylene-2,6-naphthalate. (The belt layer width BW was148 mm in all of the examples.)

TABLE 7 Comparative Comparative Exam- Exam- Example Exam- Exam- Exam-Exam- Exam- Exam- Exam- Exam- Exam- ple 15 ple 16 26 ple 27 ple 28 ple29 ple 30 ple 31 ple 32 ple 33 ple 34 ple 35 Band structure *1 IEB IEBIEB IEB IEB IEB IEB IEB IEB IEB IEB IEB Cord material *2 PEN PEN PEN PENPEN PEN PEN PEN PEN PEN PEN PEN Sectional area S 0.162 0.246 0.246 0.2460.246 0.246 0.162 0.162 0.162 0.162 0.162 0.162 <mm²> Modulus M <N/mm²>12590 8657 8657 8657 8657 8657 15230 15230 15230 15230 15230 15230Arrangement density 4 10 10 10 10 10 10 10 10 10 10 10 D <number/1 cm>Elongation resistance 81 213 213 213 213 213 246 246 246 246 246 246value K Width ratio Wb/WB 50 7 20 34 47 50 7 20 34 41 47 50 <%> Roadnoise 0.1 0.0 −1.9 −2.1 −2.2 −2.4 −0.4 −2.4 −2.5 −2.5 −2.7 −2.7performance <dB> Transit noise −0.5 −0.4 −0.4 −0.5 −0.1 −0.1 −0.4 −0.5−0.5 −0.3 −0.2 −0.1 performance <dB(A)> Rolling resistance −2 −2 1 1 0 0−2 2 2 0 0 0 performance *1 IEB represents a pair of edge band plies. *2PEN represents polyethylene-2,6-naphthalate. (The belt layer width BWwas 148 mm in all of the example s.)(Third Invention)

In the same way as in the first invention, tires having a tire size of195/65R15 91H were made by way of trial on the basis of thespecifications of Tables 4, 5, 6 and 7. Furthermore, the road noiseperformance, the transit noise performance and the rolling resistanceperformance of the respective sample tires were tested and compared inthe same way as in the first invention.

TABLE 8 Compar- ative Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam-Exam- ple 1 ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 ple 8 Band cordmaterial NYLON PEN PEN PEN PEN PEN PEN PEN PEN Edge band ply Width ratio(Wb/WB) [%] 0 7 14 20 27 34 41 47 50 Band cord sectional area S — 0.2460.246 0.246 0.246 0.246 0.246 0.246 0.246 [mm²] Band cord 2% modulus M —11235 11235 11235 11235 11235 11235 11235 11235 [N/mm²] Band cordarrangement — 10 10 10 10 10 10 10 10 density D [number/cm] Elongationresistance value K — 276 276 276 276 276 276 276 276 [N′ cord number/cm]Full band ply Number thereof 1 1 1 1 1 1 1 1 1 Band cord sectional areaS 0.248 0.246 0.246 0.246 0.246 0.246 0.246 0.246 0.246 [mm²] Band cord2% modulus M 3.228 11235 11235 11235 11235 11235 11235 11235 11235[N/mm²] Band cord arrangement 10 10 10 10 10 10 10 10 10 density D[number/cm] Elongation resistance value K 80 276 276 276 276 276 276 276276 [N′ cord number/cm] Test Road noise [dB] Standard −3.9 −4.7 −5.2−5.3 −5.6 −5.8 −6.1 −6.0 results Transit noise (OA) [dB] Standard 0 00.1 0.3 0.7 1.1 1.7 1.8 Rolling resistance [× 10⁻⁴] Standard 3 6 12 10 75 0 −1 *PEN: polyethylene-2,6-naphthalate. *The belt layer width WB was148 mm in all of the examples.

TABLE 9 Compar- ative Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam-Exam- ple 1 ple 9 ple 10 ple 11 ple 12 ple 13 ple 14 ple 15 ple 16 Bandcord material NYLON PEN PEN PEN PEN PEN PEN PEN PEN Edge band ply Widthratio (Wb/WB) [%] 0 7 14 20 27 34 41 47 50 Band cord sectional area S —0.246 0.246 0.246 0.246 0.246 0.246 0.246 0.246 [mm²] Band cord 2%modulus M — 11235 11235 11235 11235 11235 11235 11235 11235 [N/mm²] Bandcord arrangement — 14 14 14 14 14 14 14 14 density D [number/cm]Elongation resistance value K — 386 386 386 386 386 386 386 386 [N′ cordnumber/cm] Full band ply Number thereof 1 1 1 1 1 1 1 1 1 Band cordsectional area S 0.248 0.246 0.246 0.246 0.246 0.246 0.246 0.246 0.246[mm²] Band cord 2% modulus M 3.228 11235 11235 11235 11235 11235 1123511235 11235 [N/mm²] Band cord arrangement 10 14 14 14 14 14 14 14 14density D [number/cm] Elongation resistance value K 80 386 386 386 386386 386 386 386 [N′ cord number/cm] Test Road noise [dB] Standard −5.6−5.7 −5.8 −5.4 −5.6 −5.8 −5.9 −6.1 results Transit noise (OA) [dB]Standard 0.6 0.6 0.5 1.1 1.9 2.9 3.9 4.3 Rolling resistance [× 10⁻⁴]Standard 9 13 19 17 14 9 1 −2

TABLE 10 Comparative Exam- Exam- Exam- Exam- Exam- Example 1 ple 17 ple18 ple 19 ple 20 ple 21 Band cord material NYLON PEN PEN PEN PEN PENEdge band ply Width ratio (Wb/WB) [%] 0 7 20 34 47 50 Band cordsectional area S [mm²] — 0.246 0.246 0.246 0.246 0.246 Band cord 2%modulus M [N/mm²] — 11235 11235 11235 11235 11235 Band cord arrangementdensity D [number/cm] — 8 8 8 8 8 Elongation resistance value K [N′ cordnumber/cm] — 221 221 221 221 221 Full band ply Number thereof 1 1 1 1 11 Band cord sectional area S [mm²] 0.248 0.246 0.246 0.246 0.246 0.246Band cord 2% modulus M [N/mm²] 3.228 11235 11235 11235 11235 11235 Bandcord arrangement density D [number/cm] 10 8 8 8 8 8 Elongationresistance value K [N′ cord number/cm] 80 221 221 221 221 221 Test Roadnoise [dB] Standard −2.7 −4.3 −4.6 −4.7 −4.9 results Transit noise (OA)[dB] Standard −0.2 −0.2 0.3 0.8 0.9 Rolling resistance [× 10⁻⁴] Standard2 6 4 0 0

TABLE 11 Compara- tive Example Example Example Example Example ExampleExample Example Example 1 22 23 24 25 26 27 28 29 Band cord materialNYLON PEN PEN PEN PEN PEN PEN PEN PEN Edge band ply Width ratio (Wb/WB)[%] 0 7 14 20 27 34 41 47 50 Band cord sectional area S [mm²] — 0.2460.246 0.246 0.246 0.246 0.246 0.246 0.246 Band cord 2% modulus M [N/mm²]— 11235 11235 11235 11235 11235 11235 11235 11235 Band cord arrangementdensity D — 6 6 6 6 6 6 6 6 [number/cm] Elongation resistance value K —166 166 166 166 166 166 166 166 [N′ cord number/cm] Full band ply Numberthereof 1 1 1 1 1 1 1 1 1 Band cord sectional area S [mm²] 0.248 0.2460.246 0.246 0.246 0.246 0.246 0.246 0.246 Band cord 2% modulus M [N/mm²]3.228 11235 11235 11235 11235 11235 11235 11235 11235 Band cordarrangement density D 10 6 6 6 6 6 6 6 6 [number/cm] Elongationresistance value K 80 166 166 166 166 166 166 166 166 [N′ cordnumber/cm] Test results Road noise [dB] Standard −1.6 −2.0 −2.6 −2.8−2.9 −3.0 −2.9 −3.1 Transit noise (OA) [dB] Standard −0.3 −0.3 −0.3 −0.2−0.2 0 0.1 0.2 Rolling resistance [×10⁻⁴] Standard 1 2 3 2 1 0 0 −1

TABLE 12 Compara- tive Example Example Example Example Example Example 130 31 32 33 34 Band cord material NYLON PEN PEN PEN PEN PEN Edge bandply Width ratio (Wb/WB) [%] 0 7 20 34 47 50 Band cord sectional area S[mm²] — 0.246 0.246 0.246 0.246 0.246 Band cord 2% modulus M [N/mm²] —11235 11235 11235 11235 11235 Band cord arrangement density D[number/cm] — 4 4 4 4 4 Elongation resistance value K [N′ cordnumber/cm] — 110 110 110 110 110 Full band ply Number thereof 1 1 1 1 11 Band cord sectional area S [mm²] 0.248 0.246 0.246 0.246 0.246 0.246Band cord 2% modulus M [N/mm²] 3.228 11235 11235 11235 11235 11235 Bandcord arrangement density D [number/cm] 10 4 4 4 4 4 Elongationresistance value K [N′ cord number/cm] 80 110 110 110 110 110 Testresults Road noise [dB] Standard −0.5 −1.2 −1.2 −1.4 −1.3 Transit noise(OA) [dB] Standard −0.5 −0.4 −0.3 −0.2 −0.3 Rolling resistance [×10⁻⁴]Standard −2 −1 −1 −2 −2

TABLE 13 Compara- tive Example Example Example Example Example Example 135 36 37 38 39 Band cord material NYLON PEN PEN PEN PEN PEN Edge bandply Width ratio (Wb/WB) [%] 0 7 20 34 47 50 Band cord sectional area S[mm²] — 0.162 0.162 0.162 0.162 0.162 Band cord 2% modulus M [N/mm²] —11230 11230 11230 11230 11230 Band cord arrangement density D[number/cm] — 14 14 14 14 14 Elongation resistance value K [N′ cordnumber/cm] — 345 345 345 345 345 Full band ply Number thereof 1 1 1 1 11 Band cord sectional area S [mm²] 0.248 0.162 0.162 0.162 0.162 0.162Band cord 2% modulus M [N/mm²] 3.228 11230 11230 11230 11230 11230 Bandcord arrangement density D [number/cm] 10 14 14 14 14 14 Elongationresistance value K [N′ cord number/cm] 80 345 345 345 345 345 Testresults Road noise [dB] Standard −5.3 −5.5 −5.5 −5.8 −6.0 Transit noise(OA) [dB] Standard 0.4 0.4 1.6 3.4 3.8 Rolling resistance [×10⁻⁴]Standard 8 18 13 1 −2(Invention about Density Change)

Tires having a tire size of 195/65R15 91H were made by way of trial onthe basis of the specification of Table 1. The road noise performance,the transit noise performance and the rolling resistance performance ofthe respective sample tires were tested to compare the performancesthereof with each other. The thicknesses T of the topping rubbers of thebelt-form plies were unified into 0.9 mm. The widths of the belt-formplies were 4 mm in Example 18, 7 mm in Example 19, 3 mm in Example 20,14 mm in Example 22, 6 mm in Example 23, 19 mm in Example 25, and 20 mmin Example 26. All the widths in the others were 10 mm.

The test manner was the same as in the first invention. However, therolling resistance performance is converted into a point value obtainedby dividing the rolling resistance value (N) by the load (N) and thenmultiplying the resultant value by 10⁴, and is represented as a changeamount using the point value of Comparative Example 1 as a standard.Accordingly, minus representations mean decreased amounts of the pointvalues of the rolling resistance from Comparative Example 1.

The test results and so on are shown in Tables 14 to 17.

TABLE 14 Com- Com- Com- Com- Com- para- para- para- para- para- tivetive Exam- Exam- Exam- Exam- Exam- Exam- tive tive Exam- tive Exam-Exam- Exam- ple ple ple ple ple ple Exam- Exam- ple Exam- ple ple 1 ple2 1 2 3 4 5 6 ple 3 ple 4 7 ple 5 8 Specification of the band layer Bandstructure FIG. FIG. FIG. FIG. figure 19 15 20 15 Band cord NYLON PENmaterial Band cord section- 0.248 0.246 al area S [mm²] Band cord 2%3228 11235 13568 modulus M [N/mm²] Band cord arrange- 10 14 10 mentdensity D in the belt-form ply [number/cm] Elongation resis- 80 276 467334 tance value K of the belt-form ply [N′ cord number/cm] (S′ M′ D)Winding pitch of 1.0 the high density portions *1 Width BW1/W [%] 100 20100 20 100 20 of the high density portions Winding pitch of — 1.2 1.41.6 2.0 2.4 2.6 — 2.0 — 2.0 the low density portions *1 Test resultsRoad noise de- Stan- −3.4 −3.3 −3.2 −3.1 −3.0 −2.9 −5.5 −5.0 −4.4 −4.1crease value [dB] dard Transit noise Stan- 0.3 0.2 0.1 0 −0.1 −0.4 1.00.5 0.1 O. A. [dB] dard Rolling resistance Stan- 4 5 6 8 9 12 5 8 [pointvalue] dard *1 Ratio thereof to the width of the belt-form ply

TABLE 15 Com- Com- Com- Com- Com- para- para- para- para- para- tivetive tive tive tive Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam-Exam- Exam- Exam- Exam- Exam- ple ple ple ple ple ple ple ple ple pleple ple ple 6 9 8 11 7 10 9 12 10 13 4 14 15 Specification of the bandlayer Band structure FIG. 15 figure Band cord PEN material Band cordsection- 0.162 0.246 0.162 0.246 al area S [mm²] Band cord 2% 12590 865715230 12590 10001 11235 modulus M [N/mm²] Band cord arrange- 14 10 mentdensity D in the belt-form ply [number/cm] Elongation resis- 286 213 247204 162 276 tance value K of the belt-form ply [N′ cord number/cm] (S′M′ D) Winding pitch of 1.0 the high density portions *1 Width BW1/W [%]20 7 14 of the high density portions Winding pitch of — 2.0 — 2.0 — 2.0— 2.0 — 2.0 the low density portions *1 Test results Road noise de- −4.0−3.7 −2.3 −2.1 −2.2 −2.0 −2.9 −2.7 −1.5 −1.3 −3.1 0 −1.7 crease value[dB] Transit noise 0.6 0.3 0.2 0.1 0.2 0.1 0.3 0.1 0 O. A. [dB] Rollingresis- 5 8 3 4 2 4 3 5 2 3 6 −2 −2 tance [point value]

TABLE 16 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple ple ple pleple ple ple ple 16 17 18 19 20 21 22 23 Specification of the band layerBand structure figure FIG. 15 Band cord material PEN Band cord sectionalarea S [mm²] 0.246 Band cord 2% modulus M [N/mm²] 11235 Band cordarrangement density D in the 10 belt-form ply [number/cm] Elongationresistance value K of the 276 belt-form ply [N′ cord number/cm] (S′ M′D) Winding pitch of the high density 1.0 portions *1 Width BW1/W [%] ofthe high 27 34 20 density portions Winding pitch of the low density 2.01.4 2.4 2.0 1.4 portions *1 Test results Road noise decrease value [dB]−3.2 −3.3 −3.1 −3.3 −3.1 −3.3 Transit noise O. A. [dB] 0.1 0.3 0.1 0.20.1 0.2 Rolling resistance [point value] 6 5 6 5 6 5

TABLE 17 Com- Com- para- para- tive tive Exam- Exam- Exam- Exam- Exam-Exam- Exam- ple ple ple ple ple ple ple 24 25 26 12 27 12 28Specification of the band layer Band structure figure FIG. 18 FIG. 15Band cord material PEN ARAMIDE PEN Band cord sectional area S [mm²]0.248 0.246 0.111 0.246 Band cord 2% modulus M [N/mm²] 11235 29703 11235Band cord arrangement density D in 10 the belt-form ply [number/cm]Elongation resistance value K of 276 330 276 the belt-form ply [N′ cordnumber/cm] (S′ M′ D) Winding pitch of the high density 1.0 portions *1Width BW1/W [%] of the high density 20 30 0 20 0 20 portions Windingpitch of the low density 1.7 2.4 2.0 1.0 2.0 1.0 2.0 portions *1 Testresults Road noise decrease value [dB] −3.2 −3.1 −5.3 −5.0 −4.1 −3.9Transit noise O. A. [dB] 0.1 0.5 0.2 0 Rolling resistance [point value]6 5 7 8 9(Invention of the Overlap of a Band with a Belt Layer)

Tires having a tire size of 195/65R15 91H were made by way of trial onthe basis of the specifications of Tables 18 to 20. Furthermore, theroad noise performance, and the endurance performances of the respectivesample tires were tested. As band cords except Comparative Example 1,PEN cords having a sectional area S of 0.246 mm² were used. The 2%modulus M of the PEN cords was 11235 N/mm², and these were embedded at adensity of 10 per cm to form band plies. In this way, the elongationresistance value K of the band plies made of PEN was set to 276. Thewidth WB of the belt layer was set to 148 mm. On the other hand, inComparative Example 1, nylon cords having a sectional area of 0.248 mm²and a 2% modulus of 3228 N/mm² were embedded at a density of 10 per cmto form a band ply.

In Examples 10 to 12 and Comparative Examples 5 to 6, composite beltlayers using a band ply made of PEN and a band ply made of nylon cordswere formed. The manner of the test was as follows. The manner for theroad noise was the same as in the first invention. About the enduranceperformance, each of the sample tires was traveled on a drum for 200hours under the following conditions: rim: 15×6 JJ, internal pressure:200 kPa, load: 6.0 kN, and speed: 100 km/h. Thereafter, the tire was cutin the sectional direction at 4 positions in the circumferentialdirection, and then it was examined with the naked eye whether or not abelt edge looseness was generated at both ends of the belt layer in therespective sections.

TABLE 18 Compara- Compara- Compara- tive tive tive Example 1 Example 2Example 3 Example 1 Example 2 Example 3 Example 4 Example 5 Band plystructure figure FIG. 40(A) FIG. 40(A) FIG. 40(B) FIG. 23 FIG. 27 FIG.33 FIG. 34 FIG. 31 Band ply elongation resistance 80 276 276 276 276 276276 276 value K Edge band portion width [mm] — — — — 30 30 — 30 Fullband portion width [mm] 148 148 148 148 — 148 148 × 2 148 Test resultsBelt edge looseness Outer end 7e1 of the Not Not Generated Not Not NotNot Not belt layer generated generated generated generated generatedgenerated generated Outer end 7e2 of the Not Generated Generated Not NotNot Not Not belt layer generated generated generated generated generatedgenerated Road noise (change amount) [dB] Standard −3.4 −3.4 −3.4 −2.9−5.2 −5.9 −5.2

TABLE 19 Compara- tive Example 6 Example 7 Example 8 Example 9 Example 4Example 13 Example 14 Band ply structure figure FIG. 32 FIG. 28 FIG. 29FIG. 30 FIG. 23 FIG. 38 FIG. 39 Band ply elongation resistance 276 276276 276 497 276 276 value K Edge band portion width [mm] 30 30 — — — — —Full band portion width [mm] 148 148 148 × 2 148 × 2 148 165 140 Testresults Belt edge looseness Outer end 7e1 of the Not Not Not Not Not NotNot belt layer generated generated generated generated generatedgenerated generated Outer end 7e2 of the Not Not Not Not Not Not Notbelt layer generated generated generated generated generated generatedgenerated Road noise (change amount) [dB] −5.2 −5.2 −5.9 −5.9 −3.4 −3.8−2.2

TABLE 20 Comparative Comparative Example 10 Example 11 Example 12Example 5 Example 6 Band ply structure figure FIG. 35 FIG. 36 FIG. 37FIG. 40(C) FIG. 40(D) Band cord material Edge band was Edge band wasInner band was Inner band was Edge band was made of PEN, made of PEN,made of PEN, made of PEN, made of PEN, and crown and crown and outerband and outer band and crown portion was portion was was made of wasmade of portion was made of nylon made of nylon nylon nylon made ofnylon Edge band portion width [mm] 30 30 — 30 30 Full band (or crownband) width [mm] 118 148 148 148 118 Elongation resistance value K ofPEN 276 276 276 276 276 band ply Elongation resistance value K of 80 8080 80 80 nylon band ply Test results Belt edge looseness Outer end 7e1of the Not generated Not generated Not generated Generated Generatedbelt layer Outer end 7e2 of the Not generated Not generated Notgenerated Generated Not generated belt layer Road noise (change amount)[dB] −3.5 −3.7 −3.9 −3.7 −3.5

INDUSTRIALLY APPLICABILITY

The pneumatic radial tire can exhibit the effect of decreasing roadnoise while keeping deterioration in transit noise and rollingresistance below a minimum tolerance limit since the elongationresistance value K of its full band ply is set within a given range.

1. A pneumatic radial tire, comprising a carcass extending between beadportions, a belt layer arranged inside a tread portion and radiallyoutside the carcass, and a band layer arranged outside the belt layer,the band layer comprising a band ply formed by winding spirally abelt-form ply including one or plural band cords being arranged andembedded in a topping rubber, the band cord being made of polyethylenenaphthalate having a sectional area in a range of from 0.13 to 0.35 mm²and a 2% modulus of not less than 10000 N/mm², wherein when thesectional area of the band cord is represented by S (unit: mm²), the 2%modulus thereof is represented by M (unit: N/mm²), and the band cordarrangement density per cm of the band ply is represented by D (unit:cord number/cm), the elongation resistance value K (unit: N′ cordnumber/cm) specified by the following equation is set within the rangeof 99 to 700 in the band ply:K=S×M×D/100  (1).
 2. The pneumatic radial tire according to claim 1,wherein the band layer is made of one full band ply which covers almostall of the width of the belt layer, and the elongation resistance valueK (unit: N′ cord number/cm) of the full band ply is set within the rangeof 99 to
 334. 3. The pneumatic radial tire according to claim 2, whereinthe number of the band cords in the belt-form ply is at least two, andin the full band ply, at least one band cord in the belt-form ply is/arecut in a band central area centralizing the equator of the tire andhaving a width of 20 to 80% of the width BW of the belt layer.
 4. Thepneumatic radial tire according to claim 3, wherein the number of thecut band cord is not less than 0.1 time the number of the band cords inthe belt-form ply.
 5. The pneumatic radial tire according to claim 2,wherein the band ply comprises a pair of high density portions eachhaving the winding pitch of the belt-form ply being 1.0 time or less thewidth of the belt-form ply, and constituting both outer portions in thetire axial direction, and a low density portion having the winding pitchof the belt-form ply being from 1.2 to 2.6 times the width of thebelt-form ply, and being formed between the high density portions. 6.The pneumatic radial tire according to claim 5, wherein the band ply isformed by winding the belt-form ply continuously and spirally from oneof the high density portions to the other thereof.
 7. The pneumaticradial tire according to claim 5 or 6, wherein the width of the highdensity portion along the tire axial direction is from 7 to 34% of thewidth of the belt layer.
 8. The pneumatic radial tire according to claim5, wherein the thickness of the topping rubber in the belt-form ply isfrom 0.7 to 1.5 mm.
 9. The pneumatic radial tire according to claim 5,wherein the low density portion has a gradually-increasing portionwherein the winding pitch of the belt-form ply increases graduallytoward the tire equator.
 10. The pneumatic radial tire according toclaim 2, wherein a winding terminal portion constituting aone-circumference portion ahead of a winding terminal of the belt-formply is disposed at a position which does not directly contact the outerend of the belt layer along the tire axial direction.
 11. The pneumaticradial tire according to claim 10, wherein at least one part of awinding starting end portion constituting a one-circumference portion inthe rear of a winding starting end of the belt-form ply is covered withan afterward-wound belt-form ply.
 12. The pneumatic radial tireaccording to claim 10 or 11, wherein the winding terminal portion isdisposed outside the outer end of the belt layer along the tire axialdirection.
 13. The pneumatic radial tire according to claim 1, whereinthe band layer comprises a pair of edge band plies arranged at both endportions of the belt layer, about the elongation resistance value K(unit: N′ cord number/cm) and the width ratio of the width Wb of theedge band ply to the width WB of the belt layer (Wb/WB), the edge bandplies are formed as follows: (a) the elongation resistance value K isset within the range of 120 or more and less than 246, and the widthratio Wb/WB is set within the range of 0.2 or more and 0.5 or less, (b)the elongation resistance value K is set within the range of 246 or moreand less than 276, and the width ratio Wb/WB is set within the range ofmore than 0 and 0.5 or less, or (c) the elongation resistance value K isset within the range of 276 or more and 450 or less, and the width ratioWb/WB is set within the range of more than 0 and 0.41 or less.
 14. Thepneumatic radial tire according to claim 13, wherein in the edge bandplies, the elongation resistance value K is set within the range of 120or more and less than 246 and the width ratio Wb/WB is set within therange of 0.41 or more and 0.5 or less, or the elongation resistancevalue K is set within the range of 246 or more and 450 or less and thewidth ratio Wb/WB is set within the range of more than 0 and 0.14 orless.
 15. The pneumatic radial tire according to claim 13, wherein awinding terminal portion constituting a one-circumference portion aheadof a winding terminal of the belt-form ply is disposed at a positionwhich does not directly contact the outer end of the belt layer alongthe tire axial direction.
 16. The pneumatic radial tire according toclaim 15, wherein at least one part of a winding starting end portionconstituting a one-circumference portion in the rear of a windingstarting end of the belt-form ply is covered with an afterward-woundbelt-form ply.
 17. The pneumatic radial tire according to claim 15 or16, wherein the winding terminal portion is disposed outside the outerend of the belt layer along the tire axial direction.
 18. The pneumaticradial tire according to claim 1, wherein the band layer comprises onefull band ply which covers almost all of the width of this belt layerand a pair of edge band plies arranged at both end portions of the beltlayer, and the elongation resistance value K (unit: N′ cord number/cm)of the respective band plies is set within the range of 110 to
 386. 19.The pneumatic radial tire according to claim 18, wherein about theelongation resistance value K (unit: N′ cord number/cm) of the edge bandplies and the width ratio of the width Wb of the edge band ply to thewidth WB of the belt layer (Wb/WB), in the case that the elongationresistance value K is 110 or more and 170 or less, the width ratio(Wb/WB) is set to more than 0 and 0.5 or less, in the case that theelongation resistance value K is more than 170 and 280 or less, thewidth ratio (Wb/WB) is set to more than 0 and 0.07 or less, or 0.47 ormore and 0.5 or less, and in the case that the elongation resistancevalue K is more than 280 and 386 or less, the width ratio (Wb/WB) is setto 0.47 or more and 0.5 or less.
 20. The pneumatic radial tire accordingto claim 18, wherein about the elongation resistance value K (unit: N′cord number/cm) of the edge band plies and the width ratio of the widthWb of the edge band ply to the width WB of the belt layer (Wb/WB), inthe case that the elongation resistance value K is 110 or more and 280or less, the width ratio (Wb/WB) is set to more than 0 and 0.5 or less,in the case that the elongation resistance value K is more than 280 andless than 340, the width ratio (Wb/WB) is set to more than 0 and 0.4 orless, and in the case that the elongation resistance value K is 340 ormore and 386 or less, the width ratio (Wb/WB) is set to more than 0 andless than 0.28.
 21. The pneumatic radial tire according to claim 18,wherein about the elongation resistance value K (unit: N′ cordnumber/cm) of the edge band plies and the width ratio of the width Wb ofthe edge band ply to the width WB of the belt layer (Wb/WB), in the casethat the elongation resistance value K is 110 or more and 170 or less,the width ratio (Wb/WB) is set to more than 0 and 0.5 or less, and inthe case that the elongation resistance value K is more than 170 and 280or less, the width ratio (Wb/WB) is set to more than 0 and 0.07 or less,or 0.47 or more and 0.5 or less.
 22. The pneumatic radial tire accordingto claim 18, wherein a winding terminal portion constituting aone-circumference portion ahead of a winding terminal of the belt-formply is disposed at a position which does not directly contact the outerend of the belt layer along the tire axial direction.
 23. The pneumaticradial tire according to claim 22, wherein at least one part of awinding starting end portion constituting a one-circumference portion inthe rear of a winding starting end of the belt-form ply is covered withan afterward-wound belt-form ply.
 24. The pneumatic radial tireaccording to claim 22 or 23, wherein the winding terminal portion isdisposed outside the outer end of the belt layer along the tire axialdirection.
 25. The pneumatic radial tire according to claim 2, whereinthe full band ply comprises a pair of outside areas and a central areatherebetween, the central area has a width of from 20 to 80% the widthof the belt layer, and the elongation resistance of the central area isnot more than 0.9 time the elongation resistance of the outside area.26. The pneumatic radial tire according to claim 5, wherein the highdensity portion has a gradually-increasing portion wherein the windingpitch of the belt-form ply increases gradually toward the tire equator.27. The pneumatic radial tire according to claim 9 or 26, wherein thegradually-increasing portion has an increasing rate of the winding pitchof from 5 to 55%.
 28. The pneumatic radial tire according to claim 5,wherein the band layer further comprises a pair of edge band plies eachdisposed radially outside the full band ply to cover only each highdensity portion of the full band ply.